ActuatorFD wire reference

ActuatorFD 1.0 is the shared CAN-FD wire contract for 58-10, 58-40, and Model A. These definitions describe a host-tested reference; they do not establish board firmware or hardware timing qualification.

Frame format#

Extended 29-bit identifier:

priority[28:26],service[25:18],source[17:11],destination[10:4],major[3:0]

Scalars are little-endian. Floating-point values use finite IEEE-754 binary32. Node 0 is the host; nodes 1–126 are actuators; 127 is broadcast.

Zero to smallest valid CAN-FD DLC; reject nonzero padding and incorrect DLC.

Messages#

Message	Service	Priority	Content bytes	DLC bytes
emergency_disable	0	0	4	4
fault	1	1	20	20
sync	2	2	12	12
command	3	3	38	48
state	4	4	40	48
health	5	5	33	48
discover	16	6	10	12
identity	17	6	27	32
assign_address	18	6	21	24
capabilities	19	6	26	32
session_start	20	6	24	24
ack	21	6	15	16
configure	32	7	43	48
calibrate	33	7	11	12
clear_faults	34	7	12	12
firmware_begin	48	7	45	48
firmware_chunk	49	7	45	48
firmware_commit	50	7	40	48
enable	35	3	9	12

emergency_disable#

Latching disable; accepted without session authentication, never permits enable.

Offset	Field	Wire type	Unit
0	reason	u32	—

fault#

Asynchronous fault event; clearing does not enable torque.

Offset	Field	Wire type	Unit
0	session	u32	—
4	sequence	u32	—
8	fault_bits	u32	—
12	latched_bits	u32	—
16	time_us	u32	—

sync#

Coordinator monotonic time; 32-bit microseconds wrap with modular arithmetic.

Offset	Field	Wire type	Unit
0	session	u32	—
4	time_us	u32	—
8	cycle	u32	—

command#

Output-axis SI units. Modes 0 disabled, 1 torque, 2 velocity, 3 impedance. Position uses impedance with feedforward. Flags must be zero in v1.

Offset	Field	Wire type	Unit
0	session	u32	—
4	sequence	u32	—
8	execute_us	u32	—
12	valid_until_us	u32	—
16	position_rad	f32	rad
20	velocity_rad_s	f32	rad/s
24	feedforward_nm	f32	Nm
28	kp_nm_rad	f32	Nm/rad
32	kd_nm_s_rad	f32	Nm s/rad
36	mode	u8	—
37	flags	u8	—

state#

Sampled output and motor readings; estimated torque is not torque-sensor measurement. Position unwrapping status follows capabilities.

Offset	Field	Wire type	Unit
0	session	u32	—
4	sequence	u32	—
8	time_us	u32	—
12	output_position_rad	f32	rad
16	motor_position_rad	f32	rad
20	velocity_rad_s	f32	rad/s
24	iq_a	f32	A
28	estimated_torque_nm	f32	Nm
32	temperature_c	f32	degC
36	fault_bits	u32	—

health#

Lower-rate thermal, power and communication telemetry.

Offset	Field	Wire type	Unit
0	session	u32	—
4	sequence	u32	—
8	bus_voltage_v	f32	V
12	winding_temperature_c	f32	degC
16	inverter_temperature_c	f32	degC
20	uptime_ms	u32	—
24	rx_errors	u32	—
28	tx_errors	u32	—
32	mode	u8	—

discover#

Only while all joints are disabled. Unassigned devices hash unique ID and nonce into response slots; repeat with new nonce to resolve collisions.

Offset	Field	Wire type	Unit
0	nonce	u32	—
4	slot_count	u16	—
6	slot_duration_us	u32	—

identity#

Discovery response contains immutable factory unique ID.

Offset	Field	Wire type	Unit
0	nonce	u32	—
4	unique_id	bytes16	—
20	hardware_revision	u16	—
22	firmware_version	u32	—
26	node_id	u8	—

assign_address#

Target by unique ID; node IDs 1..126. Persistent address assignment requires disabled state and acknowledgement.

Offset	Field	Wire type	Unit
0	nonce	u32	—
4	unique_id	bytes16	—
20	node_id	u8	—

capabilities#

Reported configured limits must correspond to qualified revision; encoder status describes absolute/single-turn/unwrapped validity.

Offset	Field	Wire type	Unit
0	protocol_minor	u16	—
2	capability_bits	u32	—
6	continuous_torque_nm	f32	Nm
10	peak_torque_nm	f32	Nm
14	maximum_velocity_rad_s	f32	rad/s
18	watchdog_us	u32	—
22	encoder_status	u32	—

session_start#

Establish a new nonzero session while disabled; reset sequence state, require valid sync before enable.

Offset	Field	Wire type	Unit
0	session	u32	—
4	unique_id	bytes16	—
20	watchdog_us	u32	—

ack#

Transaction result: 0 success; 1 malformed; 2 state; 3 range; 4 stale; 5 unsupported; 6 integrity; 7 busy.

Offset	Field	Wire type	Unit
0	session	u32	—
4	sequence	u32	—
8	request_service	u8	—
9	result	u16	—
11	detail	u32	—

configure#

Disabled-only typed configuration transaction; op 0 read, 1 stage, 2 commit; unknown keys rejected.

Offset	Field	Wire type	Unit
0	session	u32	—
4	sequence	u32	—
8	key	u16	—
10	operation	u8	—
11	value	bytes32	—

calibrate#

Explicit supported calibration routine 0 query, 1 start, 2 abort. Factory interlock required to energize.

Offset	Field	Wire type	Unit
0	session	u32	—
4	sequence	u32	—
8	routine	u16	—
10	operation	u8	—

clear_faults#

Clear only eligible faults while disabled; does not re-enable outputs.

Offset	Field	Wire type	Unit
0	session	u32	—
4	sequence	u32	—
8	mask	u32	—

firmware_begin#

Disabled-only inactive-slot staging. Image hash is integrity, not authorization; signed manifest verified by bootloader.

Offset	Field	Wire type	Unit
0	session	u32	—
4	sequence	u32	—
8	image_bytes	u32	—
12	image_sha256	bytes32	—
44	target_slot	u8	—

firmware_chunk#

Offset-addressed idempotent chunks, unused bytes zero; ack and retransmission required.

Offset	Field	Wire type	Unit
0	session	u32	—
4	sequence	u32	—
8	offset	u32	—
12	valid_bytes	u8	—
13	data	bytes32	—

firmware_commit#

Verify complete size, hash, signature, board compatibility and antirollback before slot switch. Fault-tolerant recovery required.

Offset	Field	Wire type	Unit
0	session	u32	—
4	sequence	u32	—
8	image_sha256	bytes32	—

enable#

Explicit state transition: 0 disable, 1 request enable. Enabling requires valid sync, fresh valid sensors, hardware readiness and zero latched faults. Never supplies torque by itself.

Offset	Field	Wire type	Unit
0	session	u32	—
4	sequence	u32	—
8	enabled	u8	—