330-008E

Check Keylock Switch Position

Verify keylock switch 1 is physically turned to SOM_1 position. Check machine parameter MP7500.x for keylock switch configuration.

Never force keylock switches - damaged switches can cause safety system failures

Verify SOM_1 Recognition

Access MOD function and check current SOM status display. Confirm TNC recognizes SOM_1 mode before attempting further transitions.

Use PLC status display to monitor safety input states in real-time

Execute Proper Mode Sequence

From SOM_1, transition to desired SOM_4 mode following proper sequence: SOM_1 → SOM_4 directly, avoiding intermediate SOM_2/3 states.

Check Safety Input Status

Access PLC status screen and verify all safety inputs show proper states. Check machine parameters MP7510.x through MP7519.x for safety input assignments.

Use the safety diagnostic screen to identify which specific safety input is preventing SOM_1

Verify Emergency Stop Circuit

Ensure all E-stop buttons are pulled out and emergency stop chain is complete. Check for loose connections at safety relay terminals.

Never bypass safety circuits - always repair the root cause of safety faults

Test Door/Guard Switches

Verify all machine guards are properly closed and door switches are functioning. Check continuity and proper mounting of safety switches.

Reset Safety System

After resolving safety input issues, perform safety system reset via MOD function or dedicated reset button to re-establish SOM_1 capability.

Review SOM Configuration Parameters

Check machine parameters MP7500.0 through MP7509.x for proper SOM mode definitions and keylock switch assignments. Verify against machine documentation.

Compare current parameters with known good backup or factory defaults

Validate Safety Function Parameters

Review MP7600.x series parameters for safety function enable/disable settings that may affect SOM transitions.

Only qualified personnel should modify safety-related parameters

Perform Parameter Consistency Check

Use TNC diagnostic functions to verify parameter consistency and identify any conflicting safety configuration settings.

Review PLC Safety Logic

Access PLC program editor and examine safety-related ladder logic, particularly sections handling SOM transitions and keylock switch processing.

Look for custom interlocks or modified safety sequences that may block standard SOM transitions

Check PLC Variable States

Monitor PLC variables related to safety modes and keylock positions during attempted mode changes to identify logic conflicts.

Test with Minimal PLC Program

If possible, load a minimal PLC program to isolate whether custom logic is causing the SOM transition failure.

Test Keylock Switch Continuity

Use multimeter to verify keylock switch contacts are making proper connections in each position. Check for worn or damaged switch contacts.

De-energize safety circuits before performing continuity tests

Verify Safety Relay Operation

Check safety relay coil voltages and contact states. Look for stuck relays or coils that fail to energize properly.

Test TNC Safety Input Module

Verify proper voltage levels at TNC safety input terminals. Check for damaged input modules or loose terminal connections.

Use TNC diagnostic screens to compare expected vs. actual input states