Cyclic Synchronous Position / Velocity / Torque Modes (CiA 402)

Three CiA 402 modes where the host sends a new position, velocity, or torque setpoint once every communication cycle.

CiA 402 is a CANopen device profile for motor drives defined by CAN in Automation (corresponding to the international standard IEC 61800-7-201), also carried over EtherCAT via CoE; it specifies the drive's state machine and a set of operating modes selected through object 0x6060. The cyclic synchronous modes are numbered 8, 9, and 10: in CSP, the host sends a target position every cycle and the drive closes position, velocity, and current loops internally; in CSV, only a target velocity is sent, with the position loop kept on the host side; in CST, only a target torque is sent, with the drive handling just the current (torque) loop, and everything else computed by the host. Unlike Profile Position mode (PP, number 1), in these three modes the trajectory is interpolated entirely by the host — the drive no longer generates one itself — which requires a fixed communication period and tight synchronization across axes. Robots doing impedance control, whole-body control, or letting a reinforcement-learning policy output torque directly tend to use CST; traditional industrial trajectory tracking tends to use CSP.

ExampleControlling a humanoid's joint modules over EtherCAT at 1 kHz: with the drive set to CST (0x6060 written as 10), the host computes and writes a torque every millisecond; set to CSP (written as 8), it writes an already-interpolated target position every millisecond instead. ROS 2's ethercat_driver_ros2 CiA 402 plugin supports switching among modes 8, 9, and 10. The MIT Mode common in legged robotics is a separate, proprietary CAN protocol that bundles target position, velocity, stiffness, damping, and feedforward torque into a single command.

Also called

CSP, CSV, CST, Cyclic Synchronous Position Mode

Related

CANopen / CiA 402 Drive Profile · EtherCAT (Ethernet for Control Automation Technology) · Servo Drive (Motor Driver) · Torque Control · Cascade Control · MIT Mode

Sources

CAN in Automation: CiA 402 series – CANopen device profile for drives and motion control
ethercat_driver_ros2: Configuring a CiA402 drive（0x6060，模式 8/9/10） (Chinese)
ros2_canopen: canopen_402_driver OperationMode 枚举 (Chinese)