Workflow Overview

Harnice supports different kinds of project types, each of which have basic, distinct properties and store information in their respective ways.

When you "run" Harnice, you're taking the input files of one project, and per a set of rules that you define, output files are generated. This process is called a build.

Some projects have input and output files that are compatible with each other. Here's the basic workflow.

each gray bar is a build operation on a different project, orange is a user-defined set of build instructions, and blue is a file.

Build instructions (project as-intended)

Most projects have build instructions (a Python script), which is inspired by 3D CAD modeling. It's written directly in Python, and besides from some housekeeping that goes on in the background, is the bulk of what's happening when you build a project.

Inside the build instructions file is where you can write your rules on how to build your project. Here's some ideas about how you can express your build intent in logical language:

• If a harness mates with a device's ethernet socket, specifiy an RJ45 connector on that end of the harness.
• If a harness contains signals that drive a safety-critical valve, clad that harness with red sleeving.
• If a system has more than 9 output devices connected to an input device that has 8 inputs, throw an error.
• If a wire is conducting a thermocouple signal, use special cable and contacts.
• Specify a label to be applied to a harness whose text is derived from the name of the harness's mating device.
• If part x is called out as a component of a harness, and part x always requires tool y set to z, add a buildnote with a leader to x that says y-z.

Here is the default build instructions you get when you try to build a project for the first time. You'd add your logic in here somewhere.

Keep an eye out for how the script references files for the project it's operating on, for other projects, and how it generates outputs all in the same stroke as performing the derivation of the part.

Default harness build instructions

import math
import random

# ===========================================================================
#                 pull harness definition from system
# ===========================================================================

system_utils.import_harness_from_harnice_system(
    system_pn=rev_history.info().get("source_part_number"),
    system_rev=rev_history.info().get("source_revision"),
    system_lib_repo=rev_history.info().get("source_lib_repo"),
    system_lib_subpath=rev_history.info().get("source_subpath"),
    target_harness=rev_history.info().get("source_refdes"),
)
rev_history.overwrite(
    {
        "desc": f"HARNESS '{rev_history.info().get('source_refdes')}' FROM SYSTEM '{rev_history.info().get('source_part_number')}-{rev_history.info().get('source_revision')}'",
    }
)

# ===========================================================================
#                  HARNESS BUILD RULES
# ===========================================================================

# Connector policy lives on the parent system.
build_utils.run_instruction_from_relative(
    "connector_chooser",
    rev_history.info().get("source_part_number"),
    rev_history.info().get("source_lib_repo"),
    rev_history.info().get("source_subpath"),
    rev_history.info().get("source_revision"),
)

# If you want to define build rules local to this harness, write them here.
# Don't forget to rely on pre-defined functions and examples in the ribbon toolbar above.

# After assigning parts to instances, import them into this harness's file tree.

instances_list.raise_error_on_unassigned_connectors()

for instance in instances_list.read():
    if instance.get("item_type") in ["harness_connector", "backshell"]:
        library_utils.pull(instance)

# ===========================================================================
#          PROCESS AVAILABLE NETWORK DOWN INTO A CHOSEN NETWORK
# ===========================================================================

# available network (cad or manual) -> chosen network (modified subset) -> flattened network (visually arranged in 2D)

available_network = available_network.load()

# Assign nodes to any segments that may not have nodes attached
available_network = chosen_network.end_all_segments_in_nodes(available_network)

# Gather the collection of all instances with item_type == node
needed_nodes = []
for instance in instances_list.read():
    if instance.get("item_type") == "node":
        name = instance.get("instance_name")
        if name not in needed_nodes:
            needed_nodes.append(name)

# Ensures that every node in the list is present in the network.
missing_nodes = chosen_network.ensure_nodes_exist(
    input_network=available_network,
    set_of_required_nodes=needed_nodes,
)

# Generate geometry for required nodes that the available network did not provide.
# Set to False to raise an error instead.
if True:
    for missing_node in missing_nodes:
        existing_nodes = available_network.get("nodes") or []

        # Empty network: park at the origin. Otherwise sprout a short random
        # leg off the first existing node.
        new_node_location = [0, 0, 0]
        if existing_nodes:
            hub = existing_nodes[0]
            new_node_distance_from_hub = random.randint(6, 18)
            new_node_angle_from_x_axis = math.radians(random.randint(0, 359))
            new_node_location = [
                hub.get("location")[0] + new_node_distance_from_hub * math.cos(new_node_angle_from_x_axis),
                hub.get("location")[1] + new_node_distance_from_hub * math.sin(new_node_angle_from_x_axis),
                hub.get("location")[2],
            ]

        available_network = bundle_network_utils.new_node(
            available_network,
            new_id=missing_node,
            new_location=new_node_location,
        )

        # Connect back to the hub so the new node is not floating.
        if existing_nodes:
            available_network.setdefault("segments", []).append({
                "segment_id": f"{missing_node}_leg",
                "location_at_end_a": list(hub.get("location") or [0, 0, 0]),
                "location_at_end_b": new_node_location,
                "spline_control_points": [],
            })
else:
    if len(missing_nodes) > 0:
        raise ValueError(f"Missing node(s) {missing_nodes}")

# Find any possible solution within the network
found_solutions = chosen_network.calculate_possible_sub_networks(
    input_network=available_network,
    set_of_required_nodes=needed_nodes,
)

# Optionally prefer a solution containing particular imported segments. Leave
# these empty unless the parent system provides stable IDs worth selecting on.
preferred_segment_ids = []  # example: ["segment-1", "segment-2"]
preferred_node_ids = []  # example: ["branch-node"]
if len(found_solutions) > 1 and (preferred_segment_ids or preferred_node_ids):
    sorted_solutions = chosen_network.find_network_with(
        input_networks=found_solutions,
        segment_ids=preferred_segment_ids,
        node_ids=preferred_node_ids,
    )
    found_solutions = sorted_solutions

# Ensure only one solution is found
number_of_found_solutions = len(found_solutions)
if number_of_found_solutions != 1:
    raise ValueError(f"Available network contains {number_of_found_solutions} solution(s)")
bundle_network = found_solutions[0]


# Clock a backshell towards the next nearest node in the chosen network
# bundle_network = bundle_network_utils.clock_backshell(
#     network=bundle_network,
#     connector_group="P1",
#     towards_node="incident",
#     round_to_nearest_angle=15,
# )

# Move chosen nodes around to keep the mating faces of the connectors at the same position as available based on the size of the assigned parts
for instance in instances_list.read():
    group = instance.get("connector_group")
    node_id = f"{group}.node"
    if instance.get("item_type") == "backshell":
        bundle_network = bundle_network_utils.clock_backshell(bundle_network, group)
    elif instance.get("item_type") == "harness_connector": # if it's a connector that has no backshell, move chosen node to the connector
        if instances_list.instance_in_connector_group_with_item_type( # backshell-doesn't-exist check
            instance.get("connector_group"), "backshell"
        ):
            continue
        bundle_network = bundle_network_utils.move_node(
            bundle_network,
            node_id,
            bundle_network_utils.output_offset(instance, "3d-mate"),
        )

# ===========================================================================
#                  FLATTEN THE CHOSEN NETWORK
# ===========================================================================

# Save the chosen network back to disk
chosen_network.save(bundle_network)

# Build the flattened network
flattened_network.derive(bundle_network)


# ===========================================================================
#                  ASSIGN CABLES AND CONDUCTORS
# ===========================================================================

# Process usable cable recommendations from the system. Recommendations are
# optional, so incomplete or stale values should not make a new harness fail.
cable_recommendations = []
for instance in instances_list.read():
    if instance.get("item_type") != "conductor":
        continue

    cable_group = instance.get("cable_group")
    if cable_group not in ["", None]:
        recommendation = {
            "instance_name": instance.get("instance_name"),
            "cable_group": cable_group,
            "mpn": instance.get("mpn"),
            "lib_repo": instance.get("lib_repo"),
            "lib_subpath": instance.get("lib_subpath"),
            "cable_identifier": instance.get("cable_identifier"),
        }
        cable_recommendations.append(recommendation)
        cable_utils.prepare_for_conductor_assign(recommendation["instance_name"])

cables_created = [] # fill up with cable refdes's as they get processed
for recommendation in cable_recommendations:
    required_fields = ["mpn", "lib_repo", "cable_identifier"]
    missing_fields = [
        field
        for field in required_fields
        if recommendation.get(field) in ["", None]
    ]
    if missing_fields:
        cli.warn(
            f"Skipping incomplete cable recommendation for "
            f"'{recommendation['instance_name']}': missing "
            f"{', '.join(missing_fields)}"
        )
        continue

    cable_group = recommendation["cable_group"]
    if cable_group not in cables_created:
        cable_utils.new_cable(
            cable_group,
            recommendation["mpn"],
            recommendation["lib_repo"],
            recommendation["lib_subpath"],
        )
        cables_created.append(cable_group)

    try:
        cable_utils.assign_conductor_to_cable(
            recommendation["instance_name"],
            cable_group, # which cable instance name gets assigned
            recommendation["cable_identifier"], # which unique conductor within the cable goes here
        )
    except ValueError as error:
        cli.warn(
            f"Skipping unusable cable recommendation for "
            f"'{recommendation['instance_name']}': {error}"
        )


# assign a cable not recommended by the upstream system 
# cable_utils.new_cable(
#     "W1",
#     "M27500-22SB2T23",
#     "https://github.com/harnice/harnice-aerospace-library",
#     "M27500",
# )
# cable_utils.assign_conductor_to_cable("conductor-1", "W1", "black")
# cable_utils.assign_conductor_to_cable("conductor-2", "W1", "white")



# route conductors between their end nodes, then map each cable onto the
# segments shared by all of its conductors
cable_utils.map_cables_and_conductors_to_segments()

# ===========================================================================
#                  CALCULATE SEGMENT BUNDLE DIAMETERS
# ===========================================================================
for instance in instances_list.read():
    if instance.get("item_type") == "segment":
        cable_utils.calculate_bundle_diameter(instance.get("instance_name"))

# ===========================================================================
#                   ASSIGN BOM LINE NUMBERS
# ===========================================================================
for instance in instances_list.read():
    if instance.get("item_type") in ["harness_connector", "cable", "backshell"]:
        instances_list.modify(instance.get("instance_name"), {"bom_line_number": True})
instances_list.assign_bom_line_numbers()

# ===========================================================================
#                  ADD BUILD NOTES
# ===========================================================================
for rev_row in rev_history.read():
    if rev_history._revs_equivalent(rev_row.get("rev"), state.rev):
        note_utils.make_rev_history_notes(rev_row)

for instance in instances_list.read():
    for note in note_utils.get_lib_build_notes(instance):
        note_utils.new_note(
            "build_note", note, affectedinstances=[instance.get("instance_name")]
        )

note_utils.assign_buildnote_numbers()

# example: add notes to describe actions
# note_utils.new_note(
#     "build_note",
#     "do this",
#     affectedinstances=["X1.B.conn"]
# )
# note_utils.new_note(
#     "build_note",
#     "do that"
# )

# example: combine buildnotes if their texts are similar
# note_utils.combine_notes("Torque backshell to connector at 40 in-lbs","Torque backshell to connector at about 40 in-lbs")


# ===========================================================================
#                  PUT TOGETHER FORMBOARD SVG INSTANCE CONTENT
# ===========================================================================
instances = instances_list.read()
note_instances = []
for instance in instances:
    if instance.get("item_type") == "note":
        note_instances.append(note_utils.parse_note_instance(instance))

formboard_overview_instances = []
formboard_detail_instances = []
for instance in instances:
    if instance.get("item_type") not in [
        "harness_connector",
        "backshell",
        "segment",
        "node",
        "origin",
    ]:
        continue

    formboard_overview_instances.append(instance)
    formboard_detail_instances.append(instance)

    detail_flag_note_counter = 1
    overview_flag_note_counter = 1

    if instance.get("item_type") in ["harness_connector", "backshell"]:
        formboard_detail_instances.append(
            note_utils.make_bom_flagnote(
                instance, f"flagnote-{detail_flag_note_counter}"
            )
        )
        detail_flag_note_counter += 1

        formboard_detail_instances.append(
            note_utils.make_part_name_flagnote(
                instance, f"flagnote-{detail_flag_note_counter}"
            )
        )
        detail_flag_note_counter += 1

    if instance.get("item_type") == "harness_connector":
        formboard_overview_instances.append(
            note_utils.make_part_name_flagnote(
                instance, f"flagnote-{overview_flag_note_counter}"
            )
        )
        overview_flag_note_counter += 1

    for note_instance in note_instances:
        if note_instance.get("note_type") == "build_note":
            if instance.get("instance_name") in note_instance.get(
                "note_affected_instances"
            ):
                formboard_detail_instances.append(
                    note_utils.make_buildnote_flagnote(
                        note_instance, instance, f"flagnote-{detail_flag_note_counter}"
                    )
                )
                detail_flag_note_counter += 1

        if note_instance.get("note_type") == "rev_change_callout":
            if instance.get("instance_name") in note_instance.get(
                "note_affected_instances"
            ):
                formboard_detail_instances.append(
                    note_utils.make_rev_change_flagnote(
                        note_instance, instance, f"flagnote-{detail_flag_note_counter}"
                    )
                )
                detail_flag_note_counter += 1

# ===========================================================================
#                  BUILD HARNESS OUTPUTS
# ===========================================================================
instances = instances_list.read()
scales = {"A": 0.25, "B": 0.3, "C": 1}

build_utils.run_macro(
    "bom_exporter_bottom_up",
    "macros/harness_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="bom-1",
)
build_utils.run_macro(
    "tooling_list_exporter",
    "macros/harness_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="tool_list-1",
)
build_utils.run_macro(
    "standard_harnice_formboard",
    "macros/harness_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="formboard-overview",
    dimension=0,
    scale=scales.get("A"),
    input_instances=formboard_overview_instances,
)
build_utils.run_macro(
    "standard_harnice_formboard",
    "macros/harness_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="formboard-detail",
    scale=scales.get("C"),
    input_instances=formboard_detail_instances,
)

# Store the default trace layout styles into a variable to be used later when
# generating the GUI block diagram layouts if desired.
default_trace_overlay_style = dict(svg_utils.trace_overlay_style)

# Example of how to edit the trace layouts for various outputs. Copy and paste
# svg_utils.regenerate_trace_overlays and modify the style dict before a macro 
# to modify that macro's trace layout appearance. 
svg_utils.regenerate_trace_overlays(
    style={
        "label_font_size": 0.5,
        "segment_spacing": 1.5,
        "stroke_width": 0.5 / 96,
        "min_label_segment_length": None,
        "network_segment_stroke_width": 1.8,
        "network_segment_font_size": 11,
        "network_node_radius": 2.2,
        "network_node_font_size": 10,
    },
)
build_utils.run_macro(
    "trace_layout_visualizer",
    "macros/harness_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="conductor_layout-1",
    trace_item_types=["conductor"],
    scale=scales.get("A"),
)
build_utils.run_macro(
    "trace_layout_visualizer",
    "macros/harness_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="cable_layout-1",
    trace_item_types=["cable"],
    scale=scales.get("A"),
)
build_utils.run_macro(
    "circuit_visualizer",
    "macros/harness_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="circuitviz-1",
    input_instances=instances_list.read(),
)
build_utils.run_macro(
    "revision_history_table",
    "macros/harness_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="revhistory-1",
)

build_notes_list_instances = []
for instance in instances_list.read():
    if (
        instance.get("item_type") == "note"
        and instance.get("note_type") == "build_note"
    ):
        build_notes_list_instances.append(instance)

build_utils.run_macro(
    "build_notes_table",
    "macros/harness_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="build_notes_table-1",
    input_instances=build_notes_list_instances,
)
build_utils.run_macro(
    "wirelist_exporter",
    "macros/harness_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="wirelist-1",
    input_instances=instances_list.read(),
)
build_utils.run_macro(
    "harness_step_builder",
    "macros/harness_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="harness-step-1",
    chosen_network=bundle_network,
    input_instances=instances_list.read(),
)
# Each run_macro call is one PDF drawing (switch instances in the console to edit layout).
# page_setup is the list of pages; edit it here, not in the PDF editor.
build_utils.run_macro(
    "pdf_generator",
    "macros/harness_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="pdf_drawing-1",
    page_setup={
        "pages": [
            {
                "tblock_mpn": "harnice_tblock",
                "tblock_lib_repo": "https://github.com/harnice/harnice-general-library",
                "tblock_lib_subpath": "titleblocks/",
                "page_size_in": [11.0, 8.5],
                "tblock_anchor": "bottom-right",
                "tblock_offset_px": [40.0, 40.0],
                "text_replacements": {
                    "tblock-key-pagedesc": "overview",
                    "tblock-key-desc": rev_history.info(field="desc"),
                    "tblock-key-pn": state.partnumber("pn"),
                    "tblock-key-drawnby": rev_history.info(field="drawnby"),
                    "tblock-key-rev": state.partnumber("R"),
                    "tblock-key-scale": scales.get("A"),
                    "tblock-key-sheet": "autosheet",
                },
            },
            {
                "tblock_mpn": "harnice_tblock",
                "tblock_lib_repo": "https://github.com/harnice/harnice-general-library",
                "tblock_lib_subpath": "titleblocks/",
                "page_size_in": [11.0, 8.5],
                "tblock_anchor": "bottom-right",
                "tblock_offset_px": [40.0, 40.0],
                "text_replacements": {
                    "tblock-key-pagedesc": "to-from table",
                    "tblock-key-desc": rev_history.info(field="desc"),
                    "tblock-key-pn": state.partnumber("pn"),
                    "tblock-key-drawnby": rev_history.info(field="drawnby"),
                    "tblock-key-rev": state.partnumber("R"),
                    "tblock-key-scale": scales.get("A"),
                    "tblock-key-sheet": "autosheet",
                },
            },
            {
                "tblock_mpn": "harnice_tblock",
                "tblock_lib_repo": "https://github.com/harnice/harnice-general-library",
                "tblock_lib_subpath": "titleblocks/",
                "page_size_in": [11.0, 8.5],
                "tblock_anchor": "bottom-right",
                "tblock_offset_px": [40.0, 40.0],
                "text_replacements": {
                    "tblock-key-pagedesc": "channel map",
                    "tblock-key-desc": rev_history.info(field="desc"),
                    "tblock-key-pn": state.partnumber("pn"),
                    "tblock-key-drawnby": rev_history.info(field="drawnby"),
                    "tblock-key-rev": state.partnumber("R"),
                    "tblock-key-scale": scales.get("A"),
                    "tblock-key-sheet": "autosheet",
                },
            },
        ],
    },
)

# Reset the trace overlay style to default saved earlier to set the gui trace
# overlay style. 
svg_utils.trace_overlay_style.update(default_trace_overlay_style)

Default system build instructions

# ===========================================================================
#                CHANNEL AND PASSTHROUGH MAPPING
# ===========================================================================
# system.build() already called channel_map.new() - one row per channel endpoint.
#
# A patch is two endpoints. Each key is:
#   (device_refdes, channel_id)                        # one endpoint
#   (device_refdes, channel_id, repeat_channel_id)     # two endpoints (a face)
# 3-tuple on a single-instance channel is an error; omitting the repeat on a
# two-instance channel is an error.
# Both endpoints (and any route() hop) must be in the same group of connected
# harnesses. Unmated terminating connectors are in no group.
#
# channel_map.map(from_key, to_key=None, multi_ch_junction_key="")
#
# endpoint -> endpoint:
# channel_map.map(("MIC1", "out1"), ("PRE1", "in1"))
#
# map onto one passthrough face. That face must have no harness, or the
# last hop must be that harness that your channel is routed through
# channel_map.map(("MIC1", "out1"), ("X1", "ch0", "A"))
#
# dual-map: two map() calls to the two faces of the same passthrough.
# consumes both as patch ends; does not write a passthrough-map row.
# channel_map.map(("MIC1", "out1"), ("X1", "ch0", "A"))
# channel_map.map(("SNK1", "in1"), ("X1", "ch0", "B"))
#
# map a channel endpoint to a shared multi_ch_junction_key
# channel_map.map(("MIC1", "out1"), multi_ch_junction_key="jcn1")

# force a 1:1 patch regardless of channel-type compatibility.
# Same signal names compile by name (pos still meets pos).
# Different signal names stay pending until circuits_list.force()
# pairs every from-side signal and drops every unused to-side signal.
# The circuit keeps the from-side name. A from-side signal cannot be dropped;
# swap the endpoints so the extra name is on the to side, then drop it.
# channel_map.force(("MIC1", "out1"), ("PWR1", "in1"))
# circuits_list.force(
#     ("MIC1", "out1"),
#     {"pos": "live", "neg": "neutral"},
#     drop=["earth"],
# )

# remaining single-endpoint channels in the same group of connected harnesses,
# compatible types, alphabetical. Skips every channel with more than one endpoint.
channel_map.map_unmapped_compatibles_alphabetically()

# this system's channel map, plus the channel map imported with every child
# subsystem (recursive). Unmapped rows are omitted. A passthrough with both
# faces mapped as patch ends becomes one row between the outer devices.
# Inside a subsystem, refdes,
# harness groups, junction ids, and connector/harness chains are prefixed:
# subsystem.name, or subsystem.subsystem.name. Channel ids are not.
channel_map.flatten()

# one row per passthrough channel, plus routing context (availables per
# group / from->to type / directionality). Dual-mapped passthroughs are omitted.
passthrough_map.new()

# add manual hops here (after new, before resolve).
# passthrough_map.route(
#     to_from_channel_device_refdes,  # either end of an already-mapped patch
#     to_from_channel_id,
#     intended_device_refdes,         # the passthrough device
#     intended_channel_id=None,       # omit to pick any available channel
#     repeat_channel_id=None,         # face the from-side arrives on; omit to infer
# )
# passthrough_map.route("MIC1", "out1", "X1")
# passthrough_map.route(
#     "MIC1", "out1", "X1", intended_channel_id="ch0", repeat_channel_id="A"
# )

# shortest remaining path; writes chain_of_connectors / chain_of_harnesses
passthrough_map.resolve()

# expand every mapped patch (and its passthrough path) into conductor circuits.
# multi-ch junction rows become from_channel.signal -> mcj.signal (first type's signals)
circuits_list.new()

# ===========================================================================
#        SEED THE INSTANCES LIST FROM CIRCUITS THAT EXIST SO FAR
# ===========================================================================
system_utils.create_instances_from_circuits_list()


# ===========================================================================
#                 RUN SYSTEM DESIGN CHECKS
# ===========================================================================
connector_list = fileio.read_tsv("system connector list")
circuits = circuits_list.read()

# check for circuits with no connectors
system_utils.find_connector_with_no_circuit(connector_list, circuits)

# TODO: HARNESS VALIDATION (imported harnesses contain conductors that match the required circuits)

# ===========================================================================
#              ADD APPEARANCES TO CHANNEL TYPES AND CIRCUITS
# ===========================================================================
# Channel traces use channel_default_appearance from the channel type's
# channel_types.tsv. Circuit traces use signal_default_appearances for
# signal_of_channel_type. The maps below write an instance appearance, and
# an instance appearance that includes base_color replaces that default.
# color -> channel types that should use that color
channel_type_colors = {
    "#D59A10": [
        (1, "https://github.com/harnice/harnice-general-library"),
        (2, "https://github.com/harnice/harnice-general-library"),
    ],
    "#4039A1": [
        (5, "https://github.com/harnice/harnice-general-library"),
    ],
}

# channel type -> signal -> color
circuit_signal_colors = {
    (1, "https://github.com/harnice/harnice-general-library"): {
        "pos": "#E24B4A",
        "neg": "#2E6B9F",
    },
    (2, "https://github.com/harnice/harnice-general-library"): {
        "pos": "#E24B4A",
        "neg": "#2E6B9F",
    },
    (5, "https://github.com/harnice/harnice-general-library"): {
        "chassis": "#4039A1",
    },
}

# apply the above appearances in the instances list as a simple base-color.
for instance in instances_list.read():
    color = None
    channel_type = instance.get("this_channel_from_channel_type")
    if instance.get("item_type") == "circuit":
        for mapped_channel_type, signals in circuit_signal_colors.items():
            if channel_type == str(mapped_channel_type):
                color = signals.get(instance.get("signal_of_channel_type"))
                break
    if not color:
        for mapped_color, channel_types in channel_type_colors.items():
            if channel_type in [str(t) for t in channel_types]:
                color = mapped_color
                break
    if color:
        instances_list.modify(
            instance.get("instance_name"),
            {"appearance": {"base_color": color}},
        )

# If you need more specific appearances, you can assign a full appearance dict to an instance like this:
# {
#     "base_color": "#E24B4A",          # required fill
#     "outline_color": "black",         # optional path outline
#     "parallelstripe": ["white"],      # optional stripes along the path
#     "perpstripe": ["red", "white"],   # optional stripes across the path
#     "twisted": "RH",                  # optional "RH", "LH", or None
# }
# example: twisted red/white pos conductor for channel type 1
# circuit_signal_colors[(1, "https://github.com/harnice/harnice-general-library")]["pos"] = {
#     "base_color": "#E24B4A",
#     "outline_color": "black",
#     "parallelstripe": ["white"],
#     "twisted": "RH",
# }
# instances_list.modify(
#     instance.get("instance_name"),
#     {"appearance": circuit_signal_colors[(1, "https://github.com/harnice/harnice-general-library")]["pos"]},
# )

# ===========================================================================
#              RECOMMEND CABLES ON CIRCUITS
# ===========================================================================
# Write rules at the system level based on system metrics to suggest information that is later consumed by
# downstream harness projects about what cables to apply onto what conductors.

# this_channel_from_channel_type -> library cable fields for instances_list.modify
circuit_cable_mpns = {
    (1, "https://github.com/harnice/harnice-general-library"): {
        "mpn": "M27500-22SB2T23",
        "lib_repo": "https://github.com/harnice/harnice-aerospace-library",
        "lib_subpath": "M27500",
    },
    (2, "https://github.com/harnice/harnice-general-library"): {
        "mpn": "M27500-22SB2T23",
        "lib_repo": "https://github.com/harnice/harnice-aerospace-library",
        "lib_subpath": "M27500",
    },
}

# signal_of_channel_type -> cable identifier (must be unique in the cable JSON)
circuit_cable_identifiers = {
    "pos": "black",
    "neg": "white",
    "chassis": "drain_wire",
}

# modify the instances list per the above
cable_counter = 1
channel_to_cable = {}  # keep every channel inside its own sequentially-counted cable
for instance in instances_list.read():
    if instance.get("item_type") != "circuit":
        continue

    channel_type = chtype.parse(instance.get("this_channel_from_channel_type"))
    if channel_type in circuit_cable_mpns:
        channel_group = instance.get("channel_group")
        if channel_group not in channel_to_cable:
            channel_to_cable[channel_group] = f"cable-{cable_counter}"
            cable_counter += 1
        instances_list.modify(
            instance.get("instance_name"),
            {
                **circuit_cable_mpns[channel_type],
                "cable_group": channel_to_cable[channel_group],
                "cable_identifier": circuit_cable_identifiers.get(
                    instance.get("signal_of_channel_type")
                ),
            },
        )


# ===========================================================================
#              SUBSYSTEM SYMBOLS
# ===========================================================================
# Each run_macro call is one symbol (switch instances in the console to edit it).
# scale is applied to the system block diagram primitive in the symbol.
# Connector pins come from unique ICD connectors. The ICD is written after
# build instructions, so a second build is required after ICD changes.
# This macro also runs device signals-list / symbol-pin verification on the ICD.
scale = 0.1

build_utils.run_macro(
    "subsystem_symbol",
    "macros/system_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="subsystem-symbol-1",
    scale=scale,
)

# Orthographic drawing of the physical assembly. One view per call.
# scale is the drawing scale. lineweight is the sheet stroke in px.
build_utils.run_macro(
    "physical_model_drawing",
    "macros/system_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="physical-1",
    scale=1,
    lineweight=1,
    hidden_instances=[],
    orientation="front",
)

# Store the default trace layout styles into a variable to be used later when
# generating the GUI block diagram layouts if desired.
default_trace_overlay_style = dict(svg_utils.trace_overlay_style)

# Example of how to edit the trace layouts for various outputs. Copy and paste
# svg_utils.regenerate_trace_overlays and modify the style dict before a macro
# to modify that macro's trace layout appearance.
svg_utils.regenerate_trace_overlays(
    style={
        "label_font_size": 0.5,
        "segment_spacing": 1.5,
        "stroke_width": 0.5 / 96,
        "min_label_segment_length": None,
        "network_segment_stroke_width": 1.8,
        "network_segment_font_size": 11,
        "network_node_radius": 2.2,
        "network_node_font_size": 10,
    },
)

# Block diagram sheet. Writes {artifact_id}-master.svg for the PDF generator.
# scale is the drawing scale. Each show_* flag is one of the old sheet
# checkboxes: True draws that layer, False hides it.
build_utils.run_macro(
    "block-diagram-svg-exporter",
    "macros/system_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="block-diagram-1",
    scale=1,
    show_boundary=True,
    show_devices=True,
    show_subsystems=True,
    show_harnesses=True,
    show_mating_connectors=True,
    show_external_interface_flags=True,
    show_harness_labels=True,
    show_channel_traces=True,
    show_circuit_traces=True,
)

# Each run_macro call is one PDF file.
build_utils.run_macro(
    "pdf_generator",
    "macros/harness_artifacts",
    "https://github.com/harnice/harnice-general-library",
    artifact_id="pdf_drawing-1",
    page_setup={
        "pages": [
            {
                "tblock_mpn": "harnice_tblock",
                "tblock_lib_repo": "https://github.com/harnice/harnice-general-library",
                "tblock_lib_subpath": "titleblocks/",
                "page_size_in": [11.0, 8.5],
                "tblock_anchor": "bottom-right",
                "tblock_offset_px": [40.0, 40.0],
                "text_replacements": {
                    "tblock-key-pagedesc": "block_diagram",
                    "tblock-key-desc": rev_history.info(field="desc"),
                    "tblock-key-pn": state.partnumber("pn"),
                    "tblock-key-drawnby": rev_history.info(field="drawnby"),
                    "tblock-key-rev": state.partnumber("R"),
                    "tblock-key-scale": scale,
                    "tblock-key-sheet": "autosheet",
                },
            },
        ],
    },
)


# ===========================================================================
#              FEATURES FOR RELATIVES
# ===========================================================================
# Any other harnice project can import and these functions using build_utils.run_instruction_from_relative().
# The following functions are defaults. Adjust, remove, duplicate them as needed. Features for relatives are
# intended to be used as a cohesive set of rules by any child part such that anything derived from this sytem
# follows the same set of rules.


def connector_chooser():
    # if the device-side connector MPN is x, assign mating connector y
    mating_connector_lookup_table = {
        #       x  :   y
        "XLR3M": {
            "mpn": "NC3FXX",  # Neutrik 3-pin female cable
            "lib_repo": "https://github.com/harnice/harnice-av-library",
            "lib_subpath": "neutrik",
            "lib_rev_used_here": None,
        },
        "XLR3F": {
            "mpn": "NC3MXX",  # Neutrik 3-pin male cable
            "lib_repo": "https://github.com/harnice/harnice-av-library",
            "lib_subpath": "neutrik",
            "lib_rev_used_here": None,
        },
        "DB25F": {
            "mpn": "M24308_4-3T",  # MIL-DTL-24308 25-pin crimp plug, nickel fluorocarbon
            "lib_repo": "https://github.com/harnice/harnice-aerospace-library",
            "lib_subpath": "dsub",
            "lib_rev_used_here": None,
        },
        "DB25M": {
            "mpn": "M24308_2-3T",  # MIL-DTL-24308 25-pin crimp receptacle, nickel fluorocarbon
            "lib_repo": "https://github.com/harnice/harnice-aerospace-library",
            "lib_subpath": "dsub",
            "lib_rev_used_here": None,
        },
    }

    # if the harness connector instance is named x, assign mating connector y
    # regardless of the device-side part number. leave empty unless you mean it.
    connector_by_instance_name = {
        #       x  :   y
        # "J1": {
        #     "mpn": "NC3FXX",
        #     "lib_repo": "https://github.com/harnice/harnice-av-library",
        #     "lib_subpath": "",
        #     "lib_rev_used_here": None,
        # },
    }

    for instance in instances_list.read():
        if instance.get("item_type") != "harness_connector":
            continue

        instance_name = instance.get("instance_name")

        mate = mating_connector_lookup_table.get(
            instance.get("device_side_connector_mpn")
        )
        if mate:
            instances_list.modify(
                instance_name=instance_name,
                instance_data=mate,
            )
            continue

        mate = connector_by_instance_name.get(instance_name)
        if mate:
            instances_list.modify(
                instance_name=instance_name,
                instance_data=mate,
            )
            continue

        # per-position rules (state.harness is the child's system position name):
        # if state.harness == "H01" and instance_name == "P1":
        #     instances_list.modify(
        #         instance_name,
        #         {
        #             "mpn": "NC3FXX",
        #             "lib_repo": "https://github.com/harnice/harnice-av-library",
        #             "lib_subpath": "neutrik",
        #             "lib_rev_used_here": None,
        #         },
        #     )
        #     continue

        # family choosers (D38999, Mighty Mouse, ...) are in the connector-choosing
        # examples ribbon - insert them here, then continue if they assign an mpn.

        # No rule matched. Keep the harness building with a placeholder.
        # Artwork goes in the general library at
        # connectors/example/EXAMPLE_CONNECTOR/rev1/drawing.svg.
        cli.warn(
            f"connector_chooser could not find a solution for {instance_name}; "
            "using EXAMPLE_CONNECTOR"
        )
        instances_list.modify(
            instance_name=instance_name,
            instance_data={
                "mpn": "EXAMPLE_CONNECTOR",
                "lib_repo": "https://github.com/harnice/harnice-general-library",
                "lib_subpath": "connectors/example",
                "lib_rev_used_here": None,
            },
        )

# Reset the trace overlay style to default saved earlier to set the gui trace
# overlay style.
svg_utils.trace_overlay_style.update(default_trace_overlay_style)

Default device build instructions

# to access configuration information, use 'configuration' (a dictionary object).
# harnice will pass in defaults or the relevant refdes configs automatically.
# print(configuration)

# ---------------------------------------------------------------------------
# Device example: four XLR channels (two in, two out).
# Each channel has one instance, so repeat_channel_id stays blank.
# ---------------------------------------------------------------------------

ch_type_ids = {
    "in": (1, "https://github.com/harnice/harnice-general-library"),
    "out": (4, "https://github.com/harnice/harnice-general-library"),
    "chassis": (5, "https://github.com/harnice/harnice-general-library")
}

xlr_pinout = {
    "pos": 2,
    "neg": 3,
    "chassis": 1
}

connector_mpns = {
    "XLR3F": ["in1", "in2"],
    "XLR3M": ["out1", "out2"]
}

def mpn_for_connector(connector_name):
    for mpn, conn_list in connector_mpns.items():
        if connector_name in conn_list:
            return mpn
    return None

signals_list.new()

for connector_name in ["in1", "in2", "out1", "out2"]:
    if connector_name.startswith("in"):
        channel_type = ch_type_ids["in"]
    elif connector_name.startswith("out"):
        channel_type = ch_type_ids["out"]
    else:
        continue

    channel_name = connector_name
    connector_mpn = mpn_for_connector(connector_name)

    for signal in chtype.signals(channel_type):
        signals_list.append(
            channel_id=channel_name,
            signal=signal,
            connector_id=connector_name,
            cavity=xlr_pinout.get(signal),
            channel_type=channel_type,
            device_connector_mpn=connector_mpn
        )

    signals_list.append(
        channel_id=f"{channel_name}-shield",
        signal="chassis",
        connector_id=connector_name,
        cavity=xlr_pinout.get("chassis"),
        channel_type=ch_type_ids["chassis"],
        device_connector_mpn=connector_mpn
    )


# A passthrough is the same channel_id on exactly two connectors. Every row
# needs a repeat_channel_id, and the two repeats must differ. Use
# harness_connector_mpn when the harness owns that face.
#
#
# How to use the relevant signals list functions:
# signals_list.append(
#     channel_id="ch0",
#     repeat_channel_id="A",
#     signal="pos",
#     connector_id="A",
#     cavity=2,
#     channel_type=ch_type_ids["in"],
#     harness_connector_mpn="XLR3F",
# )
# signals_list.append(
#     channel_id="ch0",
#     repeat_channel_id="B",
#     signal="pos",
#     connector_id="B",
#     cavity=2,
#     channel_type=ch_type_ids["out"],
#     harness_connector_mpn="XLR3M",
# )
#
# Define the physical model of your device in this section. Choose from
# default macros or import your own STEP file. 
# Each macro saves with fileio.path("body"), the device's body.step.
# A paste on the physical model page writes body_images/<face>.png and a
# comment in body.step. The next macro run rewrites body.step. Rectangular
# and rack-chassis macros link again only the faces named in images=.
# The enclosure and STEP-import macros take no images argument. Comment
# that call out after the body is right, then paste. Leaving it in build.py
# drops those face links on the next run. The PNG files stay either way.
# Rectangular sketch surface "front" is the face at y = 0.
# images = {
#     "front": os.path.join(fileio.dirpath("body_images"), "front.png"),
# }
# build_utils.run_macro(
#     "build_rectangular_physical_model",
#     "macros/device_artifacts",
#     "https://github.com/harnice/harnice-general-library",
#     artifact_id="body-1",
#     params={"width": 4, "height": 2, "depth": 6},
#     images=images,
# )
# Rack sketch surface "bottom" is the face at z = 0. The front ears are "front".
# images = {
#     "bottom": os.path.join(fileio.dirpath("body_images"), "bottom.png"),
# }
# build_utils.run_macro(
#     "build_rackmount_physical_model",
#     "macros/device_artifacts",
#     "https://github.com/harnice/harnice-general-library",
#     artifact_id="body-1",
#     params={"u": 2, "depth": 10},
#     images=images,
# )
# Rack enclosure. depth and units are the macro arguments. The front panel is
# 19 inches wide and the body is 19 inches wide. 1U is 1.75in tall.
# No images argument. Comment this call out before pasting face pictures.
# build_utils.run_macro(
#     "build_rackmount_enclosure",
#     "macros/device_artifacts",
#     "https://github.com/harnice/harnice-general-library",
#     artifact_id="body-1",
#     depth=10,
#     units=2,
# )
# Imported STEP. No images argument. Comment this call out after the copy
# looks right, then paste face pictures. The next run recopies the vendor
# file and drops those links.
# build_utils.run_macro(
#     "build_physical_model_from_step",
#     "macros/device_artifacts",
#     "https://github.com/harnice/harnice-general-library",
#     artifact_id="body-1",
#     path_to_step="vendor/chassis.step",
# )

Instances Lists, Signals Lists (project as-designed)

While having a concise set of rules is important to the definition of a project, it is not always sufficient as complete digital representation of the project. There's a difference between "as-intended" (build instructions) vs "as-designed". Harnice produces "as-designed" documentation for projects in various formats depending on the project type, but the following is a core Harnice design requirement:

There shall always be one single source-of-truth representing the as-designed project, from which all outputs or dependencies are derived.

Here are the "as-designed" filetypes of each designable project type:

Project type	As-designed source of truth
systems, harnesses	instances list
device	signals list

(the other project types have more than one but I'm not sure how to defend why that's ok at time of writing)

More information about these:

Instances Lists

Interacting with Instances Lists

An instances list is a list of every physical or notional item, idea, note, part, instruction, circuit, drawing element, thing, concept literally anything that describes how to build that harness or system.

Instances lists are the single comprehensive source of truth for the project you are working on. Other inputs—especially build instructions (your Python script)—build this list, and all output documentation are derived from it.

---

Columns

Columns are automatically generated when instances_list.new() is called. Additional columns for this kind of list may be added by the user.

Column	Description
harness	the physical harness (harness refdes) that this instance is part of
instance_name	the unique name of this instance
print_name	the non-unique, human-readable name of this instance, used for printing on output documents
bom_line_number	if this instance represents a physical procurable good, it gets assigned a line number on a bill of materials
mfg	manufacturer of this instance
mpn	manufacturer part number
item_type	what this instance is: harness_connector, backshell, cable, conductor, node, segment, note, flagnote, macro, and so on
location_type	node or segment; a node is a point, a segment is a length between nodes
segment_group	the group of segments that this instance is part of
segment_order	the sequential id of this item in its segment group
connector_group	a group of co-located parts (connectors, backshells, nodes)
channel_group	other instances associated with this one because they are part of the same channel will share this value
circuit_id	which signal this component is electrically connected to
circuit_port_number	the sequential id of this item in its signal chain
node_at_end_a	end A: a node id on a segment, or a cavity instance name on a conductor
node_at_end_b	end B: a node id on a segment, or a cavity instance name on a conductor
print_name_at_end_a	human-readable name of this instance if needed, associated with 'node_at_end_a'
print_name_at_end_b	human-readable name of this instance if needed, associated with 'node_at_end_b'
parent_csys_instance_name	the other instance upon which this instance's location is based
parent_csys_outputcsys_name	the specific output coordinate system of the parent that this instance's location is based
2d_translate	dict {x, y, rotate} in the parent CSYS; used by flattened drawings
3d_translate	6DOF dict {x, y, z, alpha, beta, gamma}; α about X, γ about Z, used by STEP
absolute_rotation	drawing heading in degrees; derive writes it on nodes and segments, flagnotes use 0
csys_children	imported csys children from library attributes file
cable_group	other instances associated with this one because they are part of the same cable will share this value
cable_identifier	which conductor in that cable this instance is assigned to (unique within the cable)
length	segment arc length from derive, or the routed length of a conductor or cable
length_tolerance	tolerance kept from the flattened CSV when derive rewrites a segment
diameter	apparent diameter of a segment, used when the segment is drawn
appearance	see harnice.utils.appearance for details
device_configuration	compact JSON of filled configuration-setup answers (from BOM)
note_type	build_note, rev_change_callout, bom_item, part_name, and other note kinds
note_number	if there is a counter involved (rev, bom, build_note, etc)
note_parent	the instance the note applies to. typically don't use this in the instances list, just note_utils
note_text	the content of the note
note_affected_instances	list of instances that are affected by the note
lib_repo	publicly traceable URL of the library this instance is from
lib_subpath	path to the instance within the library (directories between the project type and the part number)
lib_desc	description of the instance per the library's revision history
lib_latest_rev	the latest revision of the instance that exists in the remote library
lib_rev_used_here	the revision of the instance that is currently used in this project
lib_status	the status of the instance per the library's revision history
lib_releaseticket	release ticket on the library revision, when that library records one
lib_datestarted	the date this instance was first added to the library
lib_datemodified	the date this instance was last modified in the library
lib_datereleased	the date this instance was released in the library, if applicable, per the library's revision history
lib_drawnby	the name of the person who drew the instance, per the library's revision history
lib_checkedby	the name of the person who checked the instance, per the library's revision history
project_editable_lib_modified	a flag to indicate if the imported contents do not match the library's version (it's been locally modified)
lib_build_notes	recommended build notes that come with the instance from the library
lib_tools	recommended tools that come with the instance from the library
attributes_json	if an instance is imported with an attributes json attached, it's added here
device_side_refdes	if device_connector, refdes of the device it plugs into
device_side_connector_id	if device_connector, name of the connector it plugs into
device_side_connector_mpn	if device_connector, mpn of the connector it plugs into
device_side_from_cavity	if circuit, cavity on the from side (from circuits list harness_from_cavity)
device_side_to_cavity	if circuit, cavity on the to side (from circuits list harness_to_cavity)
harness_side_connector_id	asserted name of the mating harness connector (from system connector list)
this_harness_from_device_refdes	if this instance is a channel, circuit, conductor, etc, the refdes of the device it interfaces with, just within this harness
this_harness_from_device_channel_id	if this instance is a channel, circuit, conductor, etc, the channel id in the device it interfaces with, just within this harness
this_harness_from_device_connector_name	if this instance is a channel, circuit, conductor, etc, the name of the connector it interfaces with, just within this harness
this_harness_to_device_refdes	if this instance is a channel, circuit, conductor, etc, the refdes of the device it plugs into just within this harness
this_harness_to_device_channel_id	if this instance is a channel, circuit, conductor, etc, the channel id in the device it plugs into, just within this harness
this_harness_to_device_connector_name	if this instance is a channel, circuit, conductor, etc, the name of the connector it plugs into, just within this harness
this_channel_from_device_refdes	if this instance is a channel, circuit, conductor, etc, the refdes of the device it interfaces with, at the very end of the channel
this_channel_from_device_channel_id	if this instance is a channel, circuit, conductor, etc, the channel id in the device it interfaces with, at the very end of the channel
this_channel_to_device_refdes	if this instance is a channel, circuit, conductor, etc, the refdes of the device it plugs into, at the very end of the channel
this_channel_to_device_channel_id	if this instance is a channel, circuit, conductor, etc, the channel id in the device it plugs into, at the very end of the channel
this_channel_from_channel_type	if this instance is a channel, circuit, conductor, etc, the type of the channel it interfaces with, at the very end of the channel
this_channel_to_channel_type	if this instance is a channel, circuit, conductor, etc, the type of the channel it plugs into, at the very end of the channel
signal_of_channel_type	if this instance is a channel, circuit, conductor, etc, the signal of the channel it interfaces with, at the very end of the channel

---

Commands

These functions are already available in build instructions as instances_list. Use them as written.

instances_list.read()

Use this when a harness or system build needs every row of the instances list in the revision that is open.

Return every row of the instances list.

The file is fileio.path("instances list"). Cells come back as strings. attribute_of parses a cell that starts with [ or {.

instances_list.new()

Use this when the project build is starting the instances list. Harness and system builds call this before the script and replace the file. A build script does not call it again.

Create a new empty instances list file with only the standard header (COLUMNS). Overwrites existing file if present.

instances_list.new_instance(instance_name, instance_data, ignore_duplicates=False)

Use this when a harness or system build needs one new item added to the instances list.

Add a new instance to the instances list.

Usage new_instance(instance_name, instance_data, ignore_duplicates=False)

Args - instance_name: String; must be unique within the list. - instance_data: Dict of column names to values. May include instance_name; if present it must match the instance_name argument or the code will fail. - ignore_duplicates: If True, does nothing when an instance with the same instance_name already exists. If False (default), raises an error on duplicate.

Returns -1 on success. Raises on invalid input or duplicate (when ignore_duplicates is False).

instances_list.remove_instance(instance_to_delete)

Use this when a harness or system build needs one item removed from the instances list.

Remove one instance from the instances list.

Args - instance_to_delete: Instance row dict (or any dict) whose instance_name key identifies the instance to remove. Matching is done by instance_name only.

instances_list.modify(instance_name, instance_data)

Use this when a harness or system build needs to change columns on an item already in the instances list.

Update columns for an existing instance by name.

Args - instance_name: The unique name of the instance to modify. - instance_data: Dict of column names to new values. Only provided keys are updated; others are unchanged.

Raises ValueError if no instance with instance_name exists.

instances_list.attribute_of(target_instance, attribute)

Use this when a harness or system build needs one column of one item in the instances list.

Return the value of one column for a single instance.

String values that look like Python literals (list or dict, e.g. starting with `[` or `{`) are parsed with `ast.literal_eval` and the parsed value is returned; otherwise the raw string is returned.

Args - target_instance: The instance_name of the instance to look up. - attribute: The column name to read (e.g. "mpn", "harness").

Returns The value of that column for the matching instance, or None if not found or attribute missing. List/dict-like strings are returned as list/dict.

instances_list.list_of_uniques(attribute)

Use this when a harness or system build needs the distinct non-empty values in one column of the instances list.

Return a list of unique non-empty values for one column across all instances.

Args - attribute: The column name to collect (e.g. "harness", "item_type").

Returns List of unique values; blanks and None are omitted. Order follows first occurrence in the instances list.

instances_list.instance_in_connector_group_with_item_type(connector_group, item_type)

Use this when a harness build needs the single connector, backshell, or other item type in one connector group.

Return the single instance in a connector group with the given item type.

Args - connector_group: The connector_group value to match. - item_type: The item_type value to match (e.g. connector, backshell).

Returns The matching instance row dict, or 0 if no match.

Raises ValueError if connector_group or item_type is blank, or if more than one instance matches.

instances_list.seed_connector_nodes()

Use this when a harness build needs a node instance for each connector group, with that group's connectors parented to the node.

Creates a node instance for each connector group and parents each connector to it.

Intended for harness build instructions after connectors exist (for example after importing a harness from a system). For each harness_connector or device_connector with a non-blank connector_group:

• Ensures {connector_group}.node exists (item_type / location_type "node")
• If the connector has no parent_csys_instance_name, sets it to that node with parent_csys_outputcsys_name "origin"

Connectors that already have a parent coordinate system are left unchanged.

instances_list.raise_error_on_unassigned_connectors(how_to_fix=None)

Use this when a harness build should stop because a harness connector still has no manufacturer part number.

Raise if any harness_connector instance has no mpn assigned.

Call this after connector assignment (parent connector_chooser and any local rules) and before library_utils.pull.

Args: - how_to_fix (str, optional): Extra sentence appended to the error. Defaults to guidance to edit the parent system's connector_chooser or assign mpn, lib_repo, and lib_subpath from the connector-choosing examples ribbon before pull.

Raises: - ValueError: If any harness connector has a blank mpn. The message lists each instance name and its device_side_connector_mpn.

instances_list.assign_bom_line_numbers()

Use this when a harness or system build needs sequential BOM line numbers on instances whose bom_line_number cell is "True".

Assign sequential BOM line numbers to instances that have bom_line_number set to "True".

Groups by MPN and assigns the same line number to all instances sharing an MPN. Requires every such instance to have a non-empty mpn. Line numbers are assigned in order of first occurrence of each MPN.

Raises ValueError if any instance marked for BOM has an empty mpn.

Signals Lists

Interacting with Signals Lists

Signals Lists define every signal going into or out of a device or disconnect. They are the primary way Harnice stores information about devices.

Signals lists are usually repetative, long, and deterministic. Harnice helps you build signals lists efficiently using build instructuons, which are python rules that build the lists for you.

---

Columns

Columns are automatically generated when signals_list.new() is called. Additional columns are ok but discouraged due to consistency. If you need more columns, use data structures in build instructions.

Column	Description
channel_id	the channel this row belongs to; the same id on every signal of that channel
repeat_channel_id	which endpoint, when the channel is a passthrough with two ends; the two repeats must differ; blank when the channel has one endpoint
channel_type	channel type string; every signal name it declares must be appended for this endpoint, and the string must parse as a channel type
signal	signal name; one of the names declared by channel_type
cavity	pin, socket, or stud this signal uses on its connector; required, and unique on that connector
connector_id	the connector that holds this signal; every signal of one endpoint uses the same connector
device_connector_mpn	manufacturer part number of the device-side connector; set this or harness_connector_mpn, not both, and use the same choice for every row of that connector
harness_connector_mpn	manufacturer part number of the harness-side connector; set this or device_connector_mpn, not both

---

Signals List Validation Checks:

(These are automatically validated when you build the device that owns the list.)

General Signals List Rules

• Every signal in the Signals List must be contained by a pre-defined channel type

  Channel Types

  Channel Types

  ---

  How are channels mapped?

  ---

  How to define a new channel type

  1. In a repository of your choice (or start with harnice-general-library on your own branch), navigate to channel_types.tsv at the library root
  2. If you want channel definitions to be private and are therefore working in a private repository, ensure the repo's path is listed in file repository_locations.csv (located at root of your harnice source code repo). The first column is the URL or traceable path, and the second column is your local path.
  3. If you find the channel_type you're looking for, temporarily note it as a touple in a notepad somewhere with format (ch_type_id, universal_library_repository).
  4. If you don't find it, make a new one. It's important to try and reduce the number of channel_types in here to reduce complexity, but it's also important that you adhere to strict and true rules about what is allowed to be mapped to what. Modifications and additions to this document should be taken and reviewed very seriously.

  Two optional columns set the default appearance. Both cells are Python dict literals, parsed with ast.literal_eval. Leave a cell blank to leave that default unset. Harnice reads the channel_types.tsv at the root of the library named by the channel type's lib_repo.

  • channel_default_appearance — one engineering appearance dict. A channel trace (channel or harness-channel) and the channel card in the connectors view use it. Example: {'base_color': '#D59A10'}.
  • signal_default_appearances — signal name to appearance dict. A circuit trace uses the entry for its signal_of_channel_type, and the connectors view uses that entry for the signal bar. Names match the signals column. Example: {'pos': {'base_color': '#E24B4A'}, 'neg': {'base_color': '#2E6B9F'}}.

  An instance appearance that already includes base_color is the appearance drawn for that trace. Traces are drawn when the project is built, so a change to these columns shows up on overlays after the next build. The connectors view reads the columns when the page opens. A trace whose resolved appearance has no base_color is the rainbow placeholder. A card or bar with no base_color keeps the console palette.

  The dict is the engineering appearance from the Appearance guide: base_color, and optionally outline_color, parallelstripe, perpstripe, and twisted. Single quotes match the rows already in the file. The separator is a tab, so a comma inside the literal stays in the cell.

  chtype.parse(val)

  Use this when a build has a channel type as stored text and needs the (channel_type_id, lib_repo) pair.

  Convert stored string into a tuple (chid:int, lib_repo:str). Handles both single tuples and extracts first tuple from lists.

  chtype.signals(channel_type)

  Use this when a system or device build needs the signal names declared for one channel type.

  Return the list of signal names associated with a specific channel type.

  Args

  • channel_type: Channel type identifier in standard tuple format (channel_type_id, lib_repo) or any string representation that parse can understand.

  Returns

  • list[str]: List of signal names from the signals column of channel_types.tsv for the matching channel_type_id. If the column is blank or the channel type cannot be found, returns an empty list.

  Data format

  • The signals column is expected to be a comma-separated string, for example: "CAN_H, CAN_L, SHIELD".

  chtype.channel_default_appearance(channel_type)

  Use this when a drawing needs the default appearance of one channel type's trace and card.

  Optional default appearance for this channel type's channel trace and card.

  Reads channel_default_appearance from the channel_types.tsv at the root of the library named by this channel type's lib_repo. The cell is a Python dict literal, parsed with ast.literal_eval (see appearance.parse). Example: {'base_color': '#D59A10'}. A blank cell returns None.

  A channel trace (item_type channel or harness-channel) and the channel card in the connectors view use this appearance. A circuit trace uses signal_default_appearances for its signal_of_channel_type instead.

  An instance appearance that already includes base_color is the appearance drawn for that trace. Traces are drawn when the project is built. The connectors view reads this column when the page opens. A trace whose resolved appearance has no base_color is the rainbow placeholder. A channel card with no base_color keeps the console palette.

  The dict is an engineering appearance: base_color plus any of outline_color, parallelstripe, perpstripe, and twisted.

  Args

  • channel_type: Channel type identifier in standard tuple format (channel_type_id, lib_repo) or any string representation that parse can understand.

  Returns

  • dict or None: Parsed appearance, or None when the cell is empty or the channel type cannot be found.

  chtype.signal_default_appearances(channel_type)

  Use this when a drawing needs the default appearance of each signal on one channel type.

  Optional default appearance for each signal of this channel type.

  Reads signal_default_appearances from the channel_types.tsv at the root of the library named by this channel type's lib_repo. The cell is a Python dict literal, parsed with ast.literal_eval: signal name to appearance dict. Example: {'pos': {'base_color': '#E24B4A'}, 'neg': {'base_color': '#2E6B9F'}}. A blank cell returns {}. Names that are not themselves dicts are dropped. Signal names match the signals column.

  A circuit trace uses the entry for its signal_of_channel_type. The connectors view uses the same entry for that signal's bar. A channel trace uses channel_default_appearance.

  An instance appearance that already includes base_color is the appearance drawn for that trace. Traces are drawn when the project is built. The connectors view reads this column when the page opens. A trace whose resolved appearance has no base_color is the rainbow placeholder. A signal bar with no base_color keeps the console palette.

  Each value is an engineering appearance: base_color plus any of outline_color, parallelstripe, perpstripe, and twisted.

  Args

  • channel_type: Channel type identifier in standard tuple format (channel_type_id, lib_repo) or any string representation that parse can understand.

  Returns

  • dict: Signal name to appearance dict. Empty when unset or when the channel type cannot be found.

  chtype.compatibles(channel_type)

  Use this when a system build needs the channel types declared compatible with one channel type, not including that type itself.

  Look up other channel types that are declared as compatible with the given channel type.

  Args

  • channel_type: Channel type identifier in standard tuple format (channel_type_id, lib_repo) or any string representation that parse can understand.

  Returns

  • list[tuple[int, str]]: List of (channel_type_id, lib_repo) tuples taken directly from the compatible_channel_types column of channel_types.tsv. Returns an empty list if no compatibles are defined or if the channel type cannot be found.

  Data format

  • The compatible_channel_types column must be an AST-parseable Python value:
    • Single tuple: (1, "library_repo")
    • List of tuples: [(1, "library_repo"), (2, "library_repo")]

  chtype.is_or_is_compatible_with(channel_type)

  Use this when a system build is validating or mapping channels and this channel type should count if it is the requested type or listed as compatible with it.

  Return the given channel type plus all channel types declared as compatible with it.

  Args

  • channel_type: Channel type identifier in standard tuple format (channel_type_id, lib_repo) or any string representation that parse can understand.

  Returns

  • list[tuple[int, str]]: List of (channel_type_id, lib_repo) tuples where the first entry is the parsed channel_type itself and the remaining entries are the compatibles returned by compatibles(channel_type).

  Typical use

  • Use this when validating or mapping channels and you want to treat a channel type as valid if it is either exactly the requested type or explicitly listed as compatible with it.

  chtype.attribute(channel_type, attribute)

  Use this when a system or device build needs an extra column from channel_types.tsv for one channel type.

  Read any additional column from channel_types.tsv for a given channel type.

  Args

  • channel_type: Channel type identifier in standard tuple format (channel_type_id, lib_repo) or any string representation that parse can understand.
  • attribute: Column header name in channel_types.tsv for the value you want to read (for example "description", "notes", "voltage_rating").

  Returns

  • Any: Value stored in the requested attribute column for the matching channel_type_id. Returns an empty list [] if the channel type cannot be found.

  Notes

  • Reads <library_root>/channel_types.tsv (same file as path()).
  • Use this for any per-channel-type metadata you've added as extra columns beyond the core ones like channel_type_id, signals, and compatible_channel_types.

  chtype.path(channel_type)

  Use this when a build needs the path of channel_types.tsv for one channel type's library checkout.

  Resolve the on-disk path to the channel_types.tsv file for a given channel type.

  Args

  • channel_type: Channel type identifier in standard tuple format (channel_type_id, lib_repo) or any string representation that parse can understand (for example "(5, 'https://github.com/harnice/harnice-general-library')").

  Returns

  • str: Absolute path to channel_types.tsv at the root of the library repository that owns the given channel type.

  Notes

  • This does not filter rows; it only locates the TSV file that defines all channel types for the given lib_repo.

• Each signal in the signals list must have every other signal defined by its channel type also present in the list.

  • you can't just define 'positive' if the channel type requires 'positive' and 'negative'

• Each signal defined in the list is contained by one or more cavities of connectors.

  • you can't "cap off" or not populate one of the signals within a channel because that changes the channel type.

• Every combination of (channel_id, signal, repeat_channel_id) must be unique within the signals list

  • you can’t have two i.e. “ch1, pos” signals on the same endpoint
  • if you need to break one signal out onto multiple conductors, you'll need to change the channel type to one that defines multiple conductors (i.e. named "ch1, pos-1")

• Each channel endpoint lives on exactly one connector_id

  • a passthrough is the same channel_id on two connectors, each with its own repeat_channel_id
  • signals that belong to one endpoint cannot be split across connectors
  • more than two endpoints on one channel_id is an error

Configurable Device Signals List Rules

A configuration is how a device is used, not what it is. The same part number can have different electrical behavior (balanced vs unbalanced, voltage setting, phantom on/off) without a new part number, as long as form, fit, and function of the hardware stay the same.

The signals list is not a pile of alternate rows that get filtered. Build instructions write one signals list for the answers currently in configuration (a dict). Harnice fills that dict from the defaults in fileio.path("configuration setup"), or—when the device is placed in a system—from that instance's answers on the block diagram / BOM.

• Declare fields in fileio.path("configuration setup"), then read them in build instructions

  • Each field has an id. In the script, use configuration["that_id"] (channel type, select, boolean, number, and so on).
  • You can have as many fields as you need. One field is enough for an SM58 that is either balanced or unbalanced. A mixing console might have a field per input (mic vs line, balanced vs unbalanced) so automatic channel mapping sees the type you actually set, and the instance records how to set the hardware up.
  • Field types, validation, show_if, and a full YAML example are in the device configurations documentation.

• The list you emit still has to obey the general signals-list rules

  • Complete endpoints, unique (channel_id, signal, repeat_channel_id), one connector per endpoint. Validation only sees the list for this configuration.

• Do not use configuration to change the physical part

  • If the connector or the hardware build changes, that is a new part number, not a configuration.
• Unused pins stay off the list
  • A pin is on the signals list only when a channel in this configuration uses it. Omitting a pin this configuration does not use is correct. A channel that is present still includes every signal its channel type defines.

Passthrough Signals List Rules

• A passthrough is exactly two endpoints of the same channel_id, each with a distinct repeat_channel_id
• The two channel types must be compatible with each other
  • this is so a patch that crosses the device still mates compatible types on both faces
• A single-endpoint channel must leave repeat_channel_id blank; a 3-tuple in map() on that channel is an error

---

---

Commands

These functions are already available in build instructions as signals_list. Use them as written.

signals_list.read(path_to_signals_list=None)

Use this when a device or system build needs the rows of a signals list: a path, a file key, or the signals list of the revision that is open.

Return signals-list rows from a path, file key, or the current project list.

signals_list.new()

Use this when a device build is starting the signals list and should replace the file that is already there.

Create a signals TSV at fileio.path("signals list") with only the header row.

signals_list.append(**kwargs)

Use this when a device build needs one signal added to the signals list.

Append one signal row. Missing optional fields are written as empty strings.

Required: channel_id, signal, cavity, connector_id, channel_type, and exactly one of device_connector_mpn or harness_connector_mpn.

Args: - channel_id: Channel this row belongs to. Use the same id on every signal of that channel. - channel_type: Channel type string. Every signal name it declares must be appended for this endpoint, and the string must parse as a channel type. - signal: Signal name. It must be one of the names declared by channel_type. - cavity: Pin, socket, or stud this signal uses on its connector. Required, and unique on that connector. - connector_id: Connector that holds this signal. Every signal of one endpoint must use the same connector. - repeat_channel_id: Which endpoint, when the channel is a passthrough with two ends. The two repeats must differ. Leave blank when the channel has one endpoint. Optional. - device_connector_mpn: Manufacturer part number of the device-side connector. Set this or harness_connector_mpn, not both, and use the same choice for every row of that connector. - harness_connector_mpn: Manufacturer part number of the harness-side connector. Set this or device_connector_mpn, not both.

signals_list.cavity_of_signal(channel_id, signal, path_to_signals_list, repeat_channel_id='')

Use this when a build needs the cavity one signal uses on a channel endpoint.

Return the cavity a signal uses on one channel endpoint.

Args: - channel_id: Channel id of the signal whose cavity you want. - signal: Signal name on that channel, such as pos or neg. - path_to_signals_list: Path, or file key, of the signals list to read. - repeat_channel_id: Which endpoint when the channel has two. Leave blank to match a single-endpoint channel. Optional.

signals_list.connector_id_of_channel(channel_id, path_to_signals_list, repeat_channel_id='')

Use this when a build needs the connector id of one channel in a signals list.

Return connector_id for a channel endpoint.

Args: - channel_id: Channel id whose connector you want. - path_to_signals_list: Path, or file key, of the signals list to read. Raises if that file does not exist. - repeat_channel_id: Which endpoint when the channel has two. Leave blank to match a single-endpoint channel. Optional.

---

Here's a more detailed diagram of the Harnice workflow including the information covered so far.

Part Numbering

Harnice is designed to work with git: every file format works well with git diff. However, even so, revisions of projects are inevitable: if you release a part, start building it, then realize something needs to change, what do you do?

    graph LR
        A[change in design required] --> B{change in form/fit/function?};
        B -->|Yes| C[new revision<br/>ABC-123-rev2];
        B -->|No| D[new part number<br/>ABC-124-rev1];

Change in form, fit and function is a common way for engineers to draw the line between rolling a rev and rolling a part number.

Harnice bakes revisions into part numbers, allowing you to spend your time worrying about engineering, not configuration management.

Before you build a project, Harnice requires a “rev folder”. Revision history and statuses of a project are stored in a csv, and Harnice will not build a revision if the "status" column is not blank. That column is where you can record if a revision has been released, superseded, obsoleted, etc.

Mapping Vocabulary

Mapping vocabulary

Group of connected harnesses:

• Harnesses linked through passthroughs (or a single standalone harness) that must be considered together. Channel mapping only pairs channels that share the same group.

Channel endpoint:

• One complete instance of a channel on one connector.

Patch:

• A pair of channel endpoints created by channel_map.map(). Stored in the channel map.

Passthrough:

• A channel with exactly two channel endpoints on the same device.

Map (verb):

• Pair two channel endpoints.

Route (verb):

• Send a patch through a passthrough (passthrough_map.route()).

Harness:

• A harness is an assembly of connectors, cables, and other electrical components that connect multiple devices together. It is the physical item that is built and installed in a system.

Channel:

• A channel is a set of electrical signals in a device that together transmit or receive information, power, etc. They have "channel_types" which define their attributes and compatibility with other channels, and contain a list of required signals (pos, neg)

Mapped channel:

• A mapped channel is a connection from one channel on a device to another. They define the functional requirement of any harness, and form the basis of which circuits are generated and where they go. The channel map is the list of mapped channels (and any still-unmapped channels). The passthrough map then routes those mapped channels through passthrough devices.

Signal:

• A signal is a physical conductive part inside a connector of a device that facilitiates electrical interface with the outside world. A signal must be part of a channel and live inside a connector.

Circuit:

• A circuit is the requirement that there must exist an electrical path between two signals of connected devices. You can assign conductors or other electrical elements along it. Instances assigned along the circuit have "circuit ids" which represent the order in which the circuit passes through them.

Conductor:

• A piece of copper, sometimes contained in a cable. Has as many properties, appearances, as you need

Cable:

• A cable is a COTS or custom physical item, purchased by length, that contains electrical conductors, and are physically installed inside harnesses.

Less important terms

• Contact:

  • The metal parts of a connector that does the actual mating with the other connector, allows for termination to a wire. Can be pins, sockets, studs, terminals, etc.

• Cavity:

  • The hole in a connector that physically holds a contact

The Workflow