21800

Verify MD 27880 PART_COUNTER bit 1 setting in Diagnostics > Machine Data > Channel Parameters. Confirm bit 1 = 1 (enabled) to activate workpiece counting.

Check current values via Diagnostics > System Variables: $AC_ACTUAL_PARTS (incremented per part completion) and $AC_REQUIRED_PARTS (target quantity from NC program or external input).

Review NC program for PART_NO or batch quantity definition commands that populate $AC_REQUIRED_PARTS. Confirm the setpoint matches actual production intent.

If alarm is undesired, disable MD 27880 bit 1 = 0, or reset $AC_ACTUAL_PARTS to 0 via PLC interface or manual reset command (G65 macro if configured).

Disabling bit 1 removes batch production safeguards; verify production control logic before modification.

Access Diagnostics > System Variables > $AC_ACTUAL_PARTS and log its value over a complete machining cycle. Identify at which points it increments (should be once per finished part only).

Check PLC program (OB1 / cycle logic) for M-code handlers or counter logic that modifies $AC_ACTUAL_PARTS. Verify increment trigger is tied to part completion signal (e.g., pallet exchange, spindle stop, unload M-code).

Review MD 27881 PART_COUNTER_CLEAR (auto-reset behavior) and MD 27882 PART_COUNTER_SPINDLE (spindle-based counting) to ensure counter behavior matches production workflow.

Manually reset $AC_ACTUAL_PARTS = 0 and re-run a known batch cycle. Compare counted parts to actual production output to validate counter alignment.

In Diagnostics > System Variables, record $AC_REQUIRED_PARTS value and compare against the NC program PART_NO parameter or DNC batch definition sent to the control.

If using external PLC or HMI input to set $AC_REQUIRED_PARTS, verify PLC bit assignment and HMI interface data type (INT/REAL). Check for data truncation or failed handshake.

Reload or re-enter the correct batch quantity into the NC program and verify $AC_REQUIRED_PARTS updates via Diagnostics. Run a test cycle to confirm counter behavior.

If alarm 21800 persists with correct setpoint, check MD 27880 bit 0 (part counter enable) and MD 27880 bit 2 (special part mode) for conflicting settings.