61523

Navigate to Diagnostics > Inputs/Outputs in the HMI to verify real-time caliper sensor voltage or digital input state. Check that the sensor shows expected switching behavior (typically 0-24V for analog or TTL for digital inputs).

Do not apply external voltage to test; use the machine's 24V reference supply only.

Physically inspect the caliper connector and wiring harness for loose pins, corrosion, or mechanical damage. Verify continuity with a multimeter on the sensor's signal line and return path.

Isolate the machine from servo power before using multimeter on analog lines near motor drives.

Confirm the caliper sensor is powered correctly by checking 24V supply at the sensor connector. Replace the caliper sensor if continuity is broken or supply voltage is absent.

In the HMI, access Machine Data > Grinding Parameters (MD 31100–31199 range). Verify MD31102 (or equivalent grinding caliper input parameter) points to the correct I/O module and channel assigned to the physical caliper sensor.

Do not change MD parameters without machine lock; coordinate with your Siemens commissioning documentation.

Cross-reference the I/O assignment in the PLC project (typically in STEP 7 or TIA Portal) to confirm the caliper input symbol matches the module/channel configured in Machine Data. Verify no duplicate or conflicting signal assignments.

Check the analog threshold (debounce/hysteresis) settings in MD 31110–31115 if using analog caliper input. Ensure the threshold window is wide enough to detect valid sensor signals without false triggering.

Perform a PLC online sync and reload the I/O map to the NCK. Reset the alarm and re-trigger the grinding cycle (CYCLE410/411/413) to confirm the caliper zero signal is now detected.

Review the grinding cycle call in the NC program; verify that cycle parameters (spindle speed, feed rate, dwell time before zero signal check) match the machine's commissioning sheet and sensor response time specification.

In the HMI, check Diagnostic > Trace or System Information to view the timestamp of the alarm versus the spindle speed and axis position at that moment. Confirm the spindle was stable and the wheel was in contact with the calibration surface.

Increase the dwell time in the grinding cycle parameter (typically P_DWELLTIME or equivalent) by 200–500 ms to allow the caliper sensor additional time to settle and output a clean zero signal before the NCK checks for it.