27124

Check machine safety circuit and hardwired emergency stop button physical state. Verify no mechanical activation of stop circuits on the machine control cabinet.

Navigate to Diagnostics > Servo > Axis Status in SINUMERIK HMI and verify STOP_A flag status per affected axis. Confirm which axis group triggered the alarm.

Verify safety PLC inputs feeding Stop A signal. Check Input Image (PI) bits mapped to STOP_A function in PLC program via OB35 (Safety) scan. Review parameter MD $MN_SAFE_STOP_A_DELAY_TIME for debounce timing.

Issue Power On command via HMI or NC START key to acknowledge alarm 27124 and re-enable axis servo control after confirming safety conditions are cleared.

Ensure all safety prerequisites are met before Power On; do not bypass safety interlock checks.

Access NCK Parameter Editor: Diagnostics > Parameters > Machine Data (MD). Locate MD $MN_SAFE_ALARM_SUPPRESS_LEVEL and note current value (typical range 0-99).

Cross-reference current MD $MN_SAFE_ALARM_SUPPRESS_LEVEL value against documented machine configuration baseline. Verify value matches original commissioning specification or post-modification intent.

If parameter value differs from specification, correct MD $MN_SAFE_ALARM_SUPPRESS_LEVEL to intended value. Perform Save and Compile (STRG+S), then restart NCK via System > Restart NCK to apply changes.

Parameter changes affecting safety alarm priority require validation per machine safety documentation and potential TÜV/certification re-approval.

Verify PROFISAFE network connectivity: Diagnostics > Communication > PROFINET IO or PROFIBUS DP status. Check for communication errors or telegram timeouts on safety-relevant devices.

Review Safety I/O module configuration in TIA Portal or equivalent engineering tool. Cross-check F-Parameter settings (F-CRC, F-Destination Address) for Stop A output mapping to SINUMERIK NCK.

Monitor safety telegram traffic using PROFINET Analyzer or equivalent diagnostic tool. Confirm Stop A safety signal is being transmitted intentionally or if spurious safety message is source of alarm.

If spurious PROFISAFE signal detected, investigate remote safety device logic and watchdog timers. Correct configuration or replace faulty safety module. Re-validate safety chain per ISO 13849-1 PLd/SIL2 minimum.

Safety network modifications require full functional safety validation and certification review before production restart.