CAN Protocol

Note

This document describes the CAN Protocol. For examples of usage, check out our CAN Bus Guide.

Overview 

The ODrive CANSimple protocol uses standard 11-bit message identifiers.

CANSimple Message ID
- node_id: The node ID of the ODrive (<axis>.config.can.node_id). Can be configured via odrivetool or the GUI.
- cmd_id: The Command ID, identifying the message type. All available commands are listed in Messages.
Messages prefixed with Set_ are messages that the host can send to the ODrive.
Messages prefixed with Get_ are messages that the ODrive can send to the host. These messages can be enabled as Cyclic Messages or requested explicitly by the master. To explicitly request a message, the master sends a message with the RTR bit set, and the ODrive responds with the same ID and corresponding payload. (A message with of RTR=0 and an empty payload can also be used, but is susceptible to collisions with the ODrive’s response.)
All values are encoded in little endian (aka Intel format, aka least significant byte first).
Floats are encoded with the standard IEEE 754 Float format.

CAN Messages - click on the message name for details
CMD ID	Name	Direction	Signals
0x000	Get_Version	ODrive → Host	Protocol_Version Hw_Version_Major Hw_Version_Minor Hw_Version_Variant Fw_Version_Major Fw_Version_Minor Fw_Version_Revision Fw_Version_Unreleased
0x001	Heartbeat	ODrive → Host	Axis_Error Axis_State Procedure_Result Trajectory_Done_Flag
0x002	Estop	Host → ODrive
0x003	Get_Error	ODrive → Host	Active_Errors Disarm_Reason
0x004	RxSdo	Host → ODrive	Opcode Endpoint_ID Reserved Value
0x005	TxSdo	ODrive → Host	Reserved0 Endpoint_ID Reserved1 Value
0x006	Set_Axis_Node_ID	Host → ODrive	Axis_Node_ID
0x007	Set_Axis_State	Host → ODrive	Axis_Requested_State
0x009	Get_Encoder_Estimates	ODrive → Host	Pos_Estimate Vel_Estimate
0x00b	Set_Controller_Mode	Host → ODrive	Control_Mode Input_Mode
0x00c	Set_Input_Pos	Host → ODrive	Input_Pos Vel_FF Torque_FF
0x00d	Set_Input_Vel	Host → ODrive	Input_Vel Input_Torque_FF
0x00e	Set_Input_Torque	Host → ODrive	Input_Torque
0x00f	Set_Limits	Host → ODrive	Velocity_Limit Current_Limit
0x011	Set_Traj_Vel_Limit	Host → ODrive	Traj_Vel_Limit
0x012	Set_Traj_Accel_Limits	Host → ODrive	Traj_Accel_Limit Traj_Decel_Limit
0x013	Set_Traj_Inertia	Host → ODrive	Traj_Inertia
0x014	Get_Iq	ODrive → Host	Iq_Setpoint Iq_Measured
0x015	Get_Temperature	ODrive → Host	FET_Temperature Motor_Temperature
0x016	Reboot	Host → ODrive
0x017	Get_Bus_Voltage_Current	ODrive → Host	Bus_Voltage Bus_Current
0x018	Clear_Errors	Host → ODrive
0x019	Set_Absolute_Position	Host → ODrive	Position
0x01a	Set_Pos_Gain	Host → ODrive	Pos_Gain
0x01b	Set_Vel_Gains	Host → ODrive	Vel_Gain Vel_Integrator_Gain
0x01c	Get_Torques	ODrive → Host	Torque_Target Torque_Estimate
0x01f	Enter_DFU_Mode	Host → ODrive

The ODrive can be configured to send some messages periodically without a request from the host. This is done by setting the desired send intervals in <odrv>.axis.config.can. An interval of 0 disables the message.

Message	Configuration (`<odrv>.axis.config.can.[...]`)	Default Interval
Heartbeat	`heartbeat_msg_rate_ms`	100 ms
Get_Encoder_Estimates	`encoder_msg_rate_ms`	10 ms
Get_Iq	`iq_msg_rate_ms`	disabled
Get_Error	`error_msg_rate_ms`	disabled
Get_Temperature	`temperature_msg_rate_ms`	disabled
Get_Bus_Voltage_Current	`bus_voltage_msg_rate_ms`	disabled
Get_Torques	`torques_msg_rate_ms`	disabled

Watchdog 

The ODrive’s watchdog timer can be used as a safety feature to disable the motor when CAN communication is disrupted.

See axis.config.enable_watchdog on how to enable the watchdog timer.

Each valid CAN message (with the correct node_id and a valid cmd_id) received by the ODrive resets its watchdog timer.

DBC Files 

DBC files are machine-readable database files that describe CAN message formats.

The CANSimple .dbc file for each firmware version can be downloaded here.

Several tools and libraries exist to ingest DBC files. For example you can use the free CANdb++ software from Vector to view the database.

Interoperability with CANopen 

ODrives can coexist with CANopen devices on the same bus if caution is taken with the node ID assignment.

The following table lists the valid combinations of node IDs for both CANopen and CANsimple.

CANOpen node IDs	ODrive CANSimple node IDs
32 … 127	0x10, 0x18, 0x20, 0x28
64 … 127	0x10, 0x11, 0x18, 0x19, 0x20, 0x21, 0x28, 0x29
96 … 127	0x10, 0x11, 0x12, 0x18, 0x19, 0x1A, 0x20, 0x21, 0x22, 0x28, 0x29, 0x2A

Messages 

Get_Version

Command ID: 0x00
Direction: ODrive → Host

Start Byte	Name	Type	Description
0	Protocol_Version	uint8	Always reported as 2
1	Hw_Version_Major	uint8	`hw_version_major`
2	Hw_Version_Minor	uint8	`hw_version_minor`
3	Hw_Version_Variant	uint8	`hw_version_variant`
4	Fw_Version_Major	uint8	`fw_version_major`
5	Fw_Version_Minor	uint8	`fw_version_minor`
6	Fw_Version_Revision	uint8	`fw_version_revision`
7	Fw_Version_Unreleased	uint8	`fw_version_unreleased`

Heartbeat

Command ID: 0x01
Direction: ODrive → Host

Start Byte	Name	Type	Description
0	Axis_Error	uint32	`<axis>.active_errors` \| `<axis>.disarm_reason`
4	Axis_State	uint8	`<axis>.current_state`
5	Procedure_Result	uint8	`<axis>.procedure_result`
6	Trajectory_Done_Flag	uint8	`<axis>.controller.trajectory_done` (0: false, 1: true)

Estop

Command ID: 0x02
Direction: Host → ODrive
Empty Payload

Causes the axis to disarm with ESTOP_REQUESTED.

Get_Error

Command ID: 0x03
Direction: ODrive → Host

Start Byte	Name	Type	Description
0	Active_Errors	uint32	`active_errors`
4	Disarm_Reason	uint32	`disarm_reason`

RxSdo

Command ID: 0x04
Direction: Host → ODrive

Start Byte	Name	Type	Description
0	Opcode	uint8	0: read, 1: write
1	Endpoint_ID	uint16	Endpoint ID as found in `flat_endpoints.json`
3	Reserved	uint8
4	Value	uint32	Data type and length depend on endpoint ID

Sent by the host to read or write from/to arbitrary parameters. See Arbitrary Parameter Access for details.

TxSdo

Command ID: 0x05
Direction: ODrive → Host

Start Byte	Name	Type	Description
0	Reserved0	uint8
1	Endpoint_ID	uint16	Endpoint ID as found in `flat_endpoints.json`
3	Reserved1	uint8
4	Value	uint32	Data type and length depend on endpoint ID

Sent by the ODrive in response to an RxSdo with Opcode=READ. See Arbitrary Parameter Access for details.

Set_Axis_Node_ID

Command ID: 0x06
Direction: Host → ODrive

Start Byte	Name	Type	Description
0	Axis_Node_ID	uint32	`node_id`

Set_Axis_State

Command ID: 0x07
Direction: Host → ODrive

Start Byte	Name	Type	Description
0	Axis_Requested_State	uint32	`requested_state`

Get_Encoder_Estimates

Command ID: 0x09
Direction: ODrive → Host

Start Byte

Name

Type

Unit

Description

0

Pos_Estimate

float32

rev

<axis>.pos_vel_mapper.pos_rel or <axis>.pos_vel_mapper.pos_abs,

depending on ODrive.Controller.Config.absolute_setpoints

4

Vel_Estimate

float32

rev/s

<axis>.pos_vel_mapper.vel

This message is sent by the ODrive periodically by default. See also Cyclic Messages.

Set_Controller_Mode

Command ID: 0x0b
Direction: Host → ODrive

Start Byte	Name	Type	Description
0	Control_Mode	uint32	`control_mode`
4	Input_Mode	uint32	`input_mode`

Set_Input_Pos

Command ID: 0x0c
Direction: Host → ODrive

Start Byte	Name	Type	Unit	Description
0	Input_Pos	float32	rev	`input_pos`
4	Vel_FF	int16	0.001 rev/s	`input_vel`
6	Torque_FF	int16	0.001 Nm	`input_torque`

Set_Input_Vel

Command ID: 0x0d
Direction: Host → ODrive

Start Byte	Name	Type	Unit	Description
0	Input_Vel	float32	rev/s	`input_vel`
4	Input_Torque_FF	float32	Nm	`input_torque`

Set_Input_Torque

Command ID: 0x0e
Direction: Host → ODrive

Start Byte	Name	Type	Unit	Description
0	Input_Torque	float32	Nm	`input_torque`

Set_Limits

Command ID: 0x0f
Direction: Host → ODrive

Start Byte	Name	Type	Unit	Description
0	Velocity_Limit	float32	rev/s	`vel_limit`
4	Current_Limit	float32	A	`current_soft_max`

Set_Traj_Vel_Limit

Command ID: 0x11
Direction: Host → ODrive

Start Byte	Name	Type	Unit	Description
0	Traj_Vel_Limit	float32	rev/s	`vel_limit`

Set_Traj_Accel_Limits

Command ID: 0x12
Direction: Host → ODrive

Start Byte	Name	Type	Unit	Description
0	Traj_Accel_Limit	float32	rev/s^2	`accel_limit`
4	Traj_Decel_Limit	float32	rev/s^2	`decel_limit`

Set_Traj_Inertia

Command ID: 0x13
Direction: Host → ODrive

Start Byte	Name	Type	Unit	Description
0	Traj_Inertia	float32	Nm/(rev/s^2)	`inertia`

Get_Iq

Command ID: 0x14
Direction: ODrive → Host

Start Byte	Name	Type	Unit	Description
0	Iq_Setpoint	float32	A	`Iq_setpoint`
4	Iq_Measured	float32	A	`Iq_measured`

Get_Temperature

Command ID: 0x15
Direction: ODrive → Host

Start Byte	Name	Type	Unit	Description
0	FET_Temperature	float32	deg C	`<axis>.motor.fet_thermistor.temperature`
4	Motor_Temperature	float32	deg C	`<axis>.motor.motor_thermistor.temperature`

Reboot

Command ID: 0x16
Direction: Host → ODrive
Empty Payload

Reboots the ODrive (if it is in IDLE). Equivalent to calling reboot().

Get_Bus_Voltage_Current

Command ID: 0x17
Direction: ODrive → Host

Start Byte	Name	Type	Unit	Description
0	Bus_Voltage	float32	V	`vbus_voltage`
4	Bus_Current	float32	A	`ibus`

Clear_Errors

Command ID: 0x18
Direction: Host → ODrive
Empty Payload

Equivalent to calling clear_errors().

Set_Absolute_Position

Command ID: 0x19
Direction: Host → ODrive

Start Byte	Name	Type	Unit	Description
0	Position	float32	rev	new position

Equivalent to calling set_abs_pos().

Set_Pos_Gain

Command ID: 0x1a
Direction: Host → ODrive

Start Byte	Name	Type	Unit	Description
0	Pos_Gain	float32	(rev/s) / rev	`pos_gain`

Set_Vel_Gains

Command ID: 0x1b
Direction: Host → ODrive

Start Byte	Name	Type	Unit	Description
0	Vel_Gain	float32	Nm / (rev/s)	`vel_gain`
4	Vel_Integrator_Gain	float32	Nm / rev	`vel_integrator_gain`

Get_Torques

Command ID: 0x1c
Direction: ODrive → Host

Start Byte	Name	Type	Unit	Description
0	Torque_Target	float32	Nm	`effective_torque_setpoint`
4	Torque_Estimate	float32	Nm	`torque_estimate`

Enter_DFU_Mode

Command ID: 0x1f
Direction: Host → ODrive
Empty Payload

Puts the ODrive into DFU mode (see ODrive Firmware Deployment System). Equivalent to calling enter_dfu_mode2().