330-0084

Check Machine-On Input Status

Navigate to MOD > System Info > PLC Status and verify X121.0 (Machine On) input status is TRUE.

Use the PLC status display to monitor input changes in real-time

Verify Main Contactor Operation

Check that the main machine contactor is energized and providing feedback to the TNC control input.

Ensure proper lockout/tagout procedures before checking electrical connections

Test Input Circuit Continuity

Measure 24VDC at the machine-on input terminal and verify wiring integrity from contactor auxiliary contacts to TNC input.

Check MP7200 parameter for custom machine-on input assignments

Review PLC Program Sequence

Access MOD > PLC Program and examine the logic that triggers the cut-out channel test command.

Look for missing interlocks or incorrect sequencing in the safety test routine

Check Test Initiation Conditions

Verify that the PLC program includes proper checks for machine-on status before issuing test commands.

Do not modify safety-related PLC code without proper authorization and documentation

Validate Safety Function Parameters

Review MP7210-MP7219 safety function parameters to ensure proper configuration of cut-out channel test conditions.

Compare current parameters with machine documentation or backup files

Check Safety Relay Status

Verify all safety relays are in the correct state and providing proper feedback signals to the TNC control.

Safety relay systems require qualified personnel for diagnosis and repair

Validate Safety Chain Integrity

Test the complete safety chain from E-stop circuits through safety relays to machine-on output signal.

Use the safety relay diagnostic LEDs to identify specific fault locations

Review Safety Parameter Settings

Check MP7200-MP7209 safety monitoring parameters for correct configuration of machine-on signal requirements.

Ensure safety relay response times match TNC monitoring parameters

Test Input Module Function

Navigate to MOD > System Info > Hardware Status and check the status of the digital input module containing the machine-on input.

Look for red status indicators or error flags in the hardware diagnostics

Perform Input Signal Test

Apply a known good 24VDC signal directly to the machine-on input terminal and verify recognition in PLC status display.

Ensure proper voltage levels and polarity when testing inputs

Check Module Connections

Inspect X121 connector and associated wiring for loose connections, corrosion, or damage affecting the machine-on input.

Reseat the X121 connector and check for proper contact pressure

Review Startup Sequence Timing

Monitor the timing between power-on, machine-on signal activation, and cut-out channel test initiation using PLC program timing.

Add appropriate delays in PLC program to allow proper signal stabilization

Check Signal Stabilization Time

Verify that adequate time is allowed for the machine-on input to be recognized by the TNC before test commands are issued.

Typical stabilization time should be 100-200ms after signal application

Adjust PLC Program Timing

Modify the PLC program to include proper interlocks ensuring machine-on status is confirmed before initiating safety tests.

Document all timing changes and verify they meet safety requirements