126-012A

Verify E-Stop Button Status

Physically check all emergency stop buttons on the machine, pendant, and control panel. Ensure all are released (twisted/pulled out to reset position). Check indicator lights showing E-stop active status.

Do not bypass emergency stop circuits. Resolve actual safety issues before proceeding.

Check PLC Emergency Stop Logic

Access PLC program (MOD > PLC > Edit/Monitor) and monitor the emergency stop chain markers (typically M4000-M4100 range). Verify that the emergency stop acknowledgment signal is being set correctly in the PLC logic.

Use the PLC marker monitor to watch real-time status of E-stop related markers while resetting buttons.

Inspect Safety Relay Module

Check the safety relay module or emergency stop monitoring hardware. Verify input signals are present and relay outputs are energized. Measure 24VDC presence at emergency stop circuit nodes.

Only qualified electricians should measure or modify safety circuit wiring.

Review Machine Parameters

Check MP7602.x (Simulation configuration) and MP1200.x (Emergency stop configuration). Ensure parameters are not forcing simulation mode when E-stop conditions exist.

Compare current MP values with machine manufacturer's default parameter set to identify deviations.

Search PLC for M118 Commands

Access PLC program (MOD > PLC > Edit) and search for M118 (activate simulation with drives and E-stop simulated) or M119 (deactivate simulation). Check if M118 is being called based on machine conditions.

Use the Find function in PLC editor (search for 'M118' and 'FUNCTION SIMULAT') to locate all simulation activation points.

Monitor Simulation Control Markers

In PLC marker monitor, observe markers M4910 (simulation mode request) and related simulation control markers (typically M4900-M4920 range). Identify which PLC logic is setting these markers.

Use the cross-reference function in PLC to track which program modules write to simulation markers.

Check Operating Mode Conditions

Verify if PLC has conditional logic that activates simulation in specific operating modes (setup, tool measurement, etc.). Review ladder logic or AWL code sections controlling mode-dependent simulation.

Some machine builders intentionally enable simulation during tool presetting or setup modes - verify this is intended behavior with machine documentation.

Deactivate Simulation via PLC

If simulation is not needed, command M119 from MDI mode or modify PLC to reset simulation markers. Ensure PLC logic includes proper conditions for simulation deactivation.

Only deactivate simulation when machine is in safe condition and all axis drives are ready.

Check Drive Status Display

Access MOD > System Information > Drive System. Review status of all configured axes and spindle drives. Look for communication errors, drive faults, or 'not ready' status indications.

Red or yellow status indicators show problematic drives. Note specific error codes displayed for each axis.

Verify EnDat/1VPP Encoder Signals

Check encoder connections and status in the drive system display. Verify EnDat encoders show valid position values and error-free communication. Check for encoder cable damage or loose connections.

Power off machine before inspecting encoder cable connections to prevent position loss or encoder damage.

Review Drive Enable Chain

Monitor PLC markers for drive enable signals (typically M4200-M4299 range). Verify that PLC is requesting drive enable and that enable confirmation markers are being received from drives.

Compare the drive enable request markers with drive ready confirmation markers to identify where the enable chain is interrupted.

Examine Event Log for Drive Errors

Access MOD > System Information > Event Log and filter for drive-related errors occurring before the 126-012A alarm. Address any drive errors (6xx, 9xx series alarms) that preceded simulation activation.

Sort event log by timestamp to see the exact sequence of events leading to automatic simulation mode entry.