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Motor not spinning

Symptom: the control software issues a Start command, the drive shows no fault, but the motor does not turn (or turns visibly slower than expected).

Quick triage

  1. Status word check. Read the drive's Status Word (Modbus address 3) — or look at the decoded status in WindTunnelControl.ps1. The interesting bits:

    • RDY_ON set → drive is ready, supply OK.
    • RDY_RUN set → drive is enabled.
    • RDY_REF set → drive is following its speed reference.
    • REMOTE set → drive is in remote mode (keypad shows REM).
    • TRIPPED set → fault is latched; see Faults and alarms.
    • OFF2, OFF3 set → emergency-stop bits are active; the drive will not start.

  2. REF1 actually written? Read REF1 back. If it is 0, the software's write did not land (or was overwritten by a CW write). If it is non-zero, the drive saw the setpoint.

  3. CW actually 0x047F? Read CW back. If it is 0x0476, the second step of the start sequence did not happen — the drive is prepared but not running.

Causes by symptom

REF1 stays at zero after writing

  • 11.03 REF1 SELECT is not 8 (COMM). The drive is ignoring fieldbus writes to REF1; restore the parameter (Parameter recovery).
  • Two clients are connected; one is overwriting REF1 with zero. Close all but one.

Drive accepts Start but coasts back to zero immediately

  • 10.01 EXT1 COMMANDS is not 10 (COMM). The drive is ignoring fieldbus start commands; restore.
  • Drive is in LOC mode. Keypad shows LOC; press LOC/REM.
  • A latched fault is being repeatedly auto-cleared. Read the fault history at the keypad.

Drive runs but at wrong speed

  • Calibration drift: the software's REF1 = RPM × 22.42 constant is no longer correct. Refresh with Calibration refresh.
  • Acceleration ramp set very long (22.02). Drive is on its way to the setpoint, just slowly.
  • Frequency limits in group 20 are clipping the request. Read 20.01 MAXIMUM FREQ and 20.02 MINIMUM FREQ.

Motor mechanical resistance

  • Test section blockage from a poorly mounted model. Stop, inspect.
  • Belt or coupling damaged. Inspect motor and fan coupling.
  • Bearing seized. Drive will trip on overcurrent quickly — see Faults and alarms.

OFF2 or OFF3 bit is set in SW

These are the drive's "off path 2" and "off path 3" emergency-stop bits. They have to be cleared in the Control Word before the drive will accept a start. The start sequence writes CW = 0x0476 which clears them; if the sequence was interrupted, write 0x0476 and wait 500 ms before retrying.

Sanity-check loop

If you cannot tell what is going on, drop down to WindTunnelControl.ps1 for raw register access. The PowerShell tool's status panel decodes the Status Word and the Control Word into named bits; that view is the cleanest one for figuring out what state the drive is in.

If even the PowerShell tool cannot operate the motor, the problem is in the drive itself (parameters, hardware, or firmware) — not in the software. Open WT_MS_<n>/debug_session.md and start parameter dumps.