Investigation sequence
Identify port and device
Record exact F81-F86 number and which HIM, cable, TCOMM, network or peripheral device belongs to that port.
Inspect cable and seating
Check DPI cable routing, connector fit, adapter seating and visible damage.
Test whether fault follows hardware
Where permitted, determine whether the fault follows a cable, HIM or adapter.
Check noise context
Look for nearby motor leads, poor grounding, shield problems, contactor switching or cable acting as an antenna.
Decide safe response
If a port-loss action is changed or masked, document machine-safety implications.
Stop conditions
- Unknown command source
- Fault action affects safe stopping
- Cable/device substitution is not allowed
- Network and internal port evidence conflict
Linked records
A DPI device or internal port link was lost. The route begins with port number, cable routing, electrical noise, connected device, adapter state and internal communication hardware evidence.
Routes F81-F86 port-loss evidence through HIM, DPI cable, TCOMM/adapter, port number, electrical noise, grounding and control-board communication context.