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.
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, with 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. Vendors may use statusword bits 8, 14 and 15, controlword bits 11 to 15, and their own objects from 0x2000; the state-machine 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.
Questions about CiA 402
What is a statusword in CiA 402?
The CiA 402 statusword is a 16-bit value at object 0x6041 that a servo drive reports to its master. Bits 0–3 identify the drive's DS402 state (Ready to Switch On, Switched On, Operation Enabled, Fault); higher bits carry mode-specific flags such as Target Reached and Following Error.
What is a controlword in CiA 402?
The CiA 402 controlword is a 16-bit value at object 0x6040 that the master writes to command DS402 state transitions. Bits 0–3 drive the state machine (Switch On, Enable Voltage, Quick Stop, Enable Operation); bit 7 resets faults on a rising edge.
How do I decode a statusword value?
Paste the value in hex or decimal into the decoder. Each bit maps to its CiA 402 name per IEC 61800-7-201, and the DS402 state machine highlights the drive's current state at the same time. Works for any conforming drive: CANopen, EtherCAT CoE, POWERLINK.
What is the difference between statusword and controlword?
The statusword (0x6041) is drive-to-master: the drive reports state. The controlword (0x6040) is master-to-drive: the PLC commands transitions. A healthy startup writes controlwords 0x06, 0x07, then 0x0F and reads statuswords that settle at 0x0237.
What does statusword 0x0237 mean?
0x0237 decodes to Operation Enabled: Ready to Switch On, Switched On, Operation Enabled, and Voltage Enabled are all set, Quick Stop is not active. It is the state a CiA 402 drive must reach to follow motion commands.
Why does my drive report Not Ready to Switch On?
Not Ready to Switch On means the drive is still initializing: STO inputs, the DC bus, or a hardware enable signal are typically not yet asserted. Resolve hardware enables first, then the drive self-transitions to Switch On Disabled.
Does CiA 402 apply to Beckhoff, Siemens, Kollmorgen, Yaskawa drives?
Yes. CiA 402 (IEC 61800-7-201) is transport-independent and implemented by Beckhoff (AX5000/AX8000), Siemens SINAMICS (via PROFIdrive mapping), Kollmorgen AKD, Yaskawa Sigma-7, Rexroth IndraDrive, Maxon EPOS4, Lenze, and Omron drives. Vendors may use statusword bits 8, 14 and 15, controlword bits 11 to 15, and their own objects from 0x2000.