# CAN protocol CAN 2.0, 1 Mbit/s, 11-bit identifiers. The identifier carries the node ID (bits 10 to 7, 0 to 15), the command ID (bits 6 to 1, 0 to 63) and, in frames from the driver, the error bit (bit 0). [Over CAN](https://docs.source-robotics.com/Spectral-BLDC-docs/110/06-operation/can/) explains how the pieces are used; this page lists them. Three kinds of message: - **Send_…** — the host sends data to the driver. A few are answered (the motion commands with Respond_data_pack_1, the gripper command with Respond_Gripper_data_pack); most are not. - **Send_Respond_…** — the host asks for data with a **remote frame** (RTR bit set, no data) under the command ID; the driver answers with a data frame under the same command ID. - **Respond_…** — frames only the driver sends. Multi-byte values are big-endian (data[0] first); floats are IEEE 754 single precision; bits inside a byte are numbered from the most significant bit (bit 7 first). ## Every message
| ID | Message | Direction | Length | Group | |---|---|---|---|---| | 0 | [Send_ESTOP](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/system/#send_estop) | host → driver | 0 | System | | 1 | [Send_Clear_Error](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/system/#send_clear_error) | host → driver | 0 | System | | 2 | [Send_data_pack_1](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/motion/#send_data_pack_1) | host → driver | 2, 5, 8 | Motion | | 3 | [Respond_data_pack_1](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/motion/#respond_data_pack_1) | driver → host | 8 | Motion | | 4 | [Send_data_pack_PD](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/motion/#send_data_pack_pd) | host → driver | 8 | Motion | | 5 | [Respond_data_pack_2](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/motion/#respond_data_pack_2) | driver → host | 0 | Motion | | 6 | [Send_data_pack_2](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/motion/#send_data_pack_2) | host → driver | not implemented | Motion | | 7 | [Respond_data_pack_3](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/motion/#respond_data_pack_3) | driver → host | 0 | Motion | | 8 | [Send_data_pack_3](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/motion/#send_data_pack_3) | host → driver | not implemented | Motion | | 9 | [Respond_Heartbeat](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/status/#respond_heartbeat) | driver → host | 0 | Status requests | | 10 | [Send_Respond_Ping](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/status/#send_respond_ping) | host → driver as a remote frame, driver → host as a data frame | 0 (remote) / 0 | Status requests | | 11 | [Send_CAN_ID](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/system/#send_can_id) | host → driver | 1 | System | | 12 | [Send_Idle](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/system/#send_idle) | host → driver | 0 | System | | 13 | [Send_Save_config](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/system/#send_save_config) | host → driver | 0 | System | | 14 | [Send_Reset](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/system/#send_reset) | host → driver | 0 | System | | 15 | [Send_Watchdog](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/system/#send_watchdog) | host → driver | 5 | System | | 16 | [Send_PD_Gains](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/gains-and-limits/#send_pd_gains) | host → driver | 8 | Gains and limits | | 17 | [Send_Current_Gains](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/gains-and-limits/#send_current_gains) | host → driver | 8 | Gains and limits | | 18 | [Send_Velocity_Gains](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/gains-and-limits/#send_velocity_gains) | host → driver | 8 | Gains and limits | | 19 | [Send_Position_Gains](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/gains-and-limits/#send_position_gains) | host → driver | 4 | Gains and limits | | 20 | [Send_Limits](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/gains-and-limits/#send_limits) | host → driver | 8 | Gains and limits | | 21 | [Send_Iq](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/motion/#send_iq) | host → driver | not implemented | Motion | | 22 | [Send_Kt](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/gains-and-limits/#send_kt) | host → driver | 4 | Gains and limits | | 23 | [Send_Respond_Temperature](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/status/#send_respond_temperature) | host → driver as a remote frame, driver → host as a data frame | 0 (remote) / 2 | Status requests | | 24 | [Send_Respond_Voltage](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/status/#send_respond_voltage) | host → driver as a remote frame, driver → host as a data frame | 0 (remote) / 2 | Status requests | | 25 | [Send_Respond_Device_Info](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/status/#send_respond_device_info) | host → driver as a remote frame, driver → host as a data frame | 0 (remote) / 7 | Status requests | | 26 | [Send_Respond_State_of_Errors](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/status/#send_respond_state_of_errors) | host → driver as a remote frame, driver → host as a data frame | 0 (remote) / 2 | Status requests | | 27 | [Send_Respond_Iq_data](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/status/#send_respond_iq_data) | host → driver as a remote frame, driver → host as a data frame | 0 (remote) / 2 | Status requests | | 28 | [Send_Respond_Encoder_data](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/status/#send_respond_encoder_data) | host → driver as a remote frame, driver → host as a data frame | 0 (remote) / 8 | Status requests | | 29 | [Send_Cyclic_command](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/system/#send_cyclic_command) | host → driver | not implemented | System | | 30 | [Send_Heartbeat_Setup](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/system/#send_heartbeat_setup) | host → driver | 4 | System | | 33 | [Send_Respond_Kt](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/status/#send_respond_kt) | host → driver as a remote frame, driver → host as a data frame | 0 (remote) / 4 | Status requests | | 34 | [Send_Voltage_Limit](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/gains-and-limits/#send_voltage_limit) | host → driver | 4 | Gains and limits | | 35 | [Send_Settings](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/system/#send_settings) | host → driver | 2 | System | | 36 | [Send_Parameter](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/parameters/#send_parameter) | host → driver | 5 | Parameters and buffers | | 37 | [Send_Get_Parameter](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/parameters/#send_get_parameter) | host → driver | 1 | Parameters and buffers | | 38 | [Respond_Parameter](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/parameters/#respond_parameter) | driver → host | 5 | Parameters and buffers | | 39 | [Send_Respond_Identity](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/status/#send_respond_identity) | host → driver as a remote frame, driver → host as a data frame | 0 (remote) / 8 | Status requests | | 40 | [Send_Respond_Telemetry](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/status/#send_respond_telemetry) | host → driver as a remote frame, driver → host as a data frame | 0 (remote) / 8 | Status requests | | 41 | [Send_Buffer_Read](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/parameters/#send_buffer_read) | host → driver | 5 | Parameters and buffers | | 42 | [Respond_Buffer_Data](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/parameters/#respond_buffer_data) | driver → host | 8 | Parameters and buffers | | 43 | [Send_Buffer_Write](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/parameters/#send_buffer_write) | host → driver | 8 | Parameters and buffers | | 44 | [Send_Sound](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/sound/#send_sound) | host → driver | 8 | Sound | | 45 | [Send_Sound_Samples](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/sound/#send_sound_samples) | host → driver | 1 to 8 | Sound | | 60 | [Respond_Gripper_data_pack](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/gripper/#respond_gripper_data_pack) | driver → host | 4 | Gripper | | 61 | [Send_gripper_data_pack](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/gripper/#send_gripper_data_pack) | host → driver | 0, 5 | Gripper | | 62 | [Send_gripper_calibrate](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/gripper/#send_gripper_calibrate) | host → driver | 0 | Gripper |
## By group - [Motion](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/motion/): the motion commands and their answers - [Gains and limits](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/gains-and-limits/): the loop gains, the limits, Kt - [Status requests](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/status/): temperature, voltage, device info, errors, current, encoder, Kt, identity, telemetry, the heartbeat - [System](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/system/): node ID, E-stop, idle, save, reset, clear, watchdog, heartbeat setup, settings - [Parameters and buffers](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/parameters/): the parameters behind Send_Parameter and Send_Get_Parameter, every one of them, and the buffers: capture, histogram, anti-cogging, encoder table - [Sound](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/sound/): tones, the queue and samples through the motor - [Gripper](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can/gripper/): the gripper command, calibration and the gripper state ## The Python library Every message the host can send has a method of the same name in `Spectral_BLDC.SpectralCAN`, listed in [Python library](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/python/). ## Tools and downloads [Build or decode a CAN frame, and download this firmware's JSON and DBC definitions](https://docs.source-robotics.com/Spectral-BLDC-docs/110/reference/can-tools/).