combine-dbc

name

combine-dbc

description

Combine multiple individual single-signal DBC files into one combined DBC at the application level. Use whenever the user wants to merge/combine/assemble several per-signal .dbc files (e.g. produced by the cansub-reverse-engineering skill under decoding-output/<application>/<signal>/<signal>.dbc) into a single application-wide DBC such as decoding-output/<application>/<application>.dbc. Re-runnable at any time as more signals are decoded. Triggers on phrasings like "combine the DBCs", "merge my signal DBCs", "build the combined/application DBC", "make one DBC from these".

combine-dbc

Combine the individual single-signal DBC files for one application into a single combined DBC, written at the application level. Built to pair with the cansub-reverse-engineering skill's output structure, and safe to re-run at any time as new signals are confirmed.

Output structure it works with

decoding-output/
  <application>/                      e.g. sensor-to-can/
    <signal>/<signal>.dbc             e.g. gauge1/gauge1.dbc   (inputs, one per signal)
    <application>.dbc                 e.g. sensor-to-can.dbc   (combined output)

DBC filenames are lowercase kebab-case; DBC signal/message identifiers inside the files use the plain/underscored form (hyphens aren't valid there).

Environment — run from the project venv

This script needs cantools, installed in the repo's project-local virtual environment at .venv/ (built from requirements.txt). In the commands below, python means the venv interpreter — .venv\Scripts\python.exe (Windows) or .venv/bin/python (macOS / Linux), not the system Python. If .venv/ does not exist yet, stop and ask the user to run the one-time setup: install.bat (Windows) or python3 -m venv .venv && .venv/bin/pip install -r requirements.txt (macOS / Linux).

Usage

Combine every confirmed signal for an application (auto-scans */*.dbc, one folder level down, which excludes the combined file itself):

python scripts/combine_dbc.py --app sensor-to-can
# -> decoding-output/sensor-to-can/sensor-to-can.dbc

Options:

• --app <name> — application folder under --base (default base decoding-output). Output defaults to <app-dir>/<app>.dbc.
• --app-dir <path> — point at an application folder directly (alternative to --app/--base).
• --inputs a/a.dbc b/b.dbc — combine an explicit list (relative to the app dir) instead of auto-scanning.
• --out <path> — override the combined-DBC output path.

Behaviour

• Signals sharing a CAN frame id are merged into one message.
• A re-merged signal with the same name replaces the previous definition, so re-running after re-decoding a signal is idempotent (no duplicates).
• The combined <application>.dbc at the app-dir root is never fed back into itself (it's excluded from the */*.dbc scan).
• Prints the inputs it combined and a per-message signal summary.

Notes

• Requires cantools (already a dependency of the reverse-engineering toolchain).
• This is the structured, all-at-once combine. The reverse-engineering skill also ships a lower-level merge_dbc.py that folds in one DBC at a time; prefer combine-dbc for assembling the whole application DBC.