# CAN frame tool and downloads

Build or inspect a frame using the command definitions of this manual's firmware release. All calculations
run in your browser; the tool does not connect to an adapter or send commands to hardware.

## Downloads

[Command definitions (JSON)](https://docs.source-robotics.com/STEPFOC-docs/108/assets/can/protocol-V108.json) · [Position DBC](https://docs.source-robotics.com/STEPFOC-docs/108/assets/can/protocol-V108-position.dbc) · [Velocity DBC](https://docs.source-robotics.com/STEPFOC-docs/108/assets/can/protocol-V108-velocity.dbc) · [Current DBC](https://docs.source-robotics.com/STEPFOC-docs/108/assets/can/protocol-V108-current.dbc)

The JSON includes the firmware tag, source commit, message IDs, every documented layout and its bit order.
The DBC files cover **nodes 0 to 13**, with both the clean and fault-bit identifiers of driver replies.
Reserved commands are omitted. Values use the firmware's native units: ticks, ticks/s, mA and the units in
the [CAN reference](https://docs.source-robotics.com/STEPFOC-docs/108/reference/can/).

Choose the DBC for the `Send_data_pack_1` layout your host sends:

| File | Command layout |
|---|---|
| Position DBC | 8 bytes: position, speed feedforward, current feedforward |
| Velocity DBC | 5 bytes: speed, current feedforward |
| Current DBC | 2 bytes: current |

The three layouts share a CAN identifier. DBC cannot select a layout from the frame's length, so load the
matching file; the browser decoder below handles all three lengths. Other message layouts are the same in
each download.

An RTR request uses the same identifier as its data reply. DBC describes the **data reply**; it does not
represent the request's RTR flag or the empty gripper status poll. Both are supported by the browser tool.

The gripper's two object-detection bits have an unusual order: bit 5 is the low bit, bit 4 the high bit.
The DBC signal `gripper_object_detection_raw` retains the wire value and supplies text labels (raw 2 =
object while closing, raw 1 = object while opening). The browser decoder converts that pair to the firmware's
numeric status (1 = closing, 2 = opening).

## Try a frame

The example `0x07A`, data `C8 1E 01 2C C0`, is a command to gripper node 0: position 200, speed 30,
current 300 mA, activate and action set, E-stop and release direction clear. These are an illustration of the
encoding; the device's current and motion limits still apply. Select another message above the fields to build
one of its documented forms. To inspect a reply, enter its identifier and data bytes below.

<div class="can-tool" data-schema="../../assets/can/protocol-V108.json" markdown="0">
  <p class="can-tool__status" role="status">Loading the firmware's command definitions…</p>
  <fieldset><legend>Build a frame</legend>
    <label for="ct-node">Node ID (0–13)</label><input id="ct-node" name="node" type="number" min="0" max="13" step="1" value="0">
    <label for="ct-command">Message and layout</label><select id="ct-command" name="command"></select>
    <label><input name="error" type="checkbox"> Driver reply has an active fault (error bit 1)</label>
    <div class="can-tool__fields"></div>
    <button type="button" name="build" class="md-button md-button--primary">Build frame</button>
    <pre class="can-tool__built" aria-live="polite"></pre>
    <button type="button" name="use" class="md-button">Use this frame in the decoder</button>
  </fieldset>
  <fieldset><legend>Decode a frame</legend>
    <label for="ct-id">CAN identifier (hex)</label><input id="ct-id" name="identifier" type="text" value="0x07A" spellcheck="false">
    <label for="ct-data">Data bytes (hex, up to eight)</label><input id="ct-data" name="data" type="text" value="C8 1E 01 2C C0" spellcheck="false">
    <label><input name="remote" type="checkbox"> Remote request (RTR; no payload)</label>
    <button type="button" name="decode" class="md-button md-button--primary">Decode frame</button>
    <div class="can-tool__decoded" aria-live="polite"></div>
  </fieldset>
  <noscript>Enable JavaScript for the frame tool, or use the reference tables and downloads above.</noscript>
</div>

!!! success "Check"
    The example decodes to the values above. Change the identifier to `0x1FA` to see the same command
    addressed to node 3. An invalid length or out-of-range field produces an explanation instead of a frame.

For wiring, termination, host timing and recovery, use [Over CAN](https://docs.source-robotics.com/STEPFOC-docs/108/06-operation/can/). To look up a
message's purpose and accepted lengths, use the [CAN reference](https://docs.source-robotics.com/STEPFOC-docs/108/reference/can/).