CiA 402 Statusword & Controlword Decoder
Side-by-side DS402 servo drive decoder.
The CiA 402 statusword (object 0x6041) is a 16-bit value a servo drive reports to its master; the controlword (0x6040) is the 16-bit value the master writes back to command state transitions. Enter either value in any base, toggle bits, and see the drive's position on the DS402 state machine update in real time.
Controlword
master → drive · 0x6040- 0 SO Switch On Part of the core transition pattern (SO+EV+QS+EO).
- 1 EV Enable Voltage Must be 1 to leave Switch On Disabled. 0 = Disable Voltage (coast).
- 2 QS Quick Stop Active-low: 0 commands Quick Stop, 1 means no quick stop.
- 3 EO Enable Operation Must be 1 together with SO+EV+QS to reach Operation Enabled.
- 4 OMS1 Operation Mode Specific PP: New Setpoint (rising edge). HM: Start Homing. IP: Enable Interpolation.
- 5 OMS2 Operation Mode Specific PP: Change Set Immediately (1 = abort current, 0 = buffer).
- 6 OMS3 Operation Mode Specific PP: Absolute / Relative (0 = absolute, 1 = relative target).
- 7 FR Fault Reset Edge-triggered 0→1. Clears Fault if cause removed. Do not hold high.
- 8 H Halt Stops motion per 0x605D without leaving Operation Enabled.
- 9 OMS4 Operation Mode Specific PP: Change on Setpoint. Other modes: reserved.
- 10 R Reserved Shall be 0 per the CiA 402 profile.
- 11 MS1 Manufacturer Specific Vendor-defined. EPOS4: endless movement toggle. Copley: input shaping.
- 12 MS2 Manufacturer Specific Vendor-defined.
- 13 MS3 Manufacturer Specific Vendor-defined.
- 14 MS4 Manufacturer Specific Vendor-defined.
- 15 MS5 Manufacturer Specific Vendor-defined.
Statusword
drive → master · 0x6041- 0 RTSO Ready to Switch On DC bus ready. Set in Ready to Switch On, Switched On, Operation Enabled, Quick Stop Active.
- 1 SO Switched On Power stage on. Set in Switched On, Operation Enabled, Quick Stop Active.
- 2 OE Operation Enabled PWM modulating, motor under control. Set in Operation Enabled and Quick Stop Active only.
- 3 F Fault Drive in Fault or Fault Reaction Active. Read 0x603F for the fault code.
- 4 VE Voltage Enabled High voltage (DC bus) present and OK.
- 5 QS Quick Stop Active-low: 1 = no quick stop, 0 = quick stop commanded. Inverted by spec.
- 6 SOD Switch On Disabled Drive disabled. Set only in Switch On Disabled state.
- 7 W Warning Vendor-defined warning. No state change. Check vendor warning register.
- 8 MS Manufacturer Specific Vendor-defined. Yaskawa: brake. Beckhoff: motion active. Elmo: motor-on.
- 9 REM Remote Fieldbus controlword is being processed. 0 = drive on local/keypad control.
- 10 TR Target Reached Setpoint reached within window. Meaning depends on mode (PP/PV/HM/CS*).
- 11 ILA Internal Limit Active Setpoint clamped by software position, torque, or velocity limit.
- 12 OMS1 Operation Mode Specific PP: Setpoint Ack. HM: Homing Attained. IP: IP active. CS*: Drive follows command.
- 13 OMS2 Operation Mode Specific PP/CSP: Following Error. PV: Max Slippage. HM: Homing Error.
- 14 MS2 Manufacturer Specific Vendor-defined. Commonly: AKD brake, Yaskawa tuning, Beckhoff TxPDO toggle.
- 15 MS3 Manufacturer Specific Vendor-defined. Commonly: STO status, warning-latched, homing subphase.
Compare two captured values Before / after — which bits flipped?
More about CiA 402
CiA 402 is the CANopen device profile for drives and motion control, standardised as IEC 61800-7-201. It defines the object dictionary entries, state machine, and operating modes every conforming servo drive exposes — Profile Position, Profile Velocity, Cyclic Sync Position, Torque, and Homing among them. The profile is transport-independent: the same statusword and controlword semantics apply whether the drive sits on CANopen, EtherCAT over CoE, POWERLINK, or Sercos. Vendor-specific extensions live above bit 15; the lower bits are portable across Beckhoff, Siemens, Kollmorgen, Yaskawa, Rexroth, Lenze, Maxon, and Omron. See the full CiA 402 state-machine walkthrough for every transition.
The statusword at 0x6041 is read-only from the master's perspective — the drive writes it to report state. The controlword at 0x6040 is write-only from the master's perspective — the PLC writes it to request transitions. Bits 0–3 of the statusword (Ready to Switch On, Switched On, Operation Enabled, Fault) identify the drive's position in the DS402 state machine; bits 8–15 carry operation-mode-specific flags such as Target Reached and Following Error. The controlword uses bits 0–3 for state commands and bit 7 for fault reset. For every controlword bit in every state, see the controlword cookbook.