Runnable simulator field guide
VFD fault-reset PLC scenario: test checklist
Direct answer
The learner can preserve fault identity, remove the initiating cause, prove safe reset conditions and prevent unexpected automatic restart.
Written for drive and PLC learners designing a controlled response to a VFD trip rather than issuing an unconditional reset pulse.
Scenario setup
Fault code and timestamp, trip cause, run request, command source, enable, coast state, reset input, ready state, restart policy and operator authority.
I/O and state map
Process or electrical condition through drive protection, fault latch, fieldbus or terminals, PLC state, reset request, ready feedback and deliberate restart.
Normal run
A declared fault stops the model, retains useful evidence, accepts one reset only after permissives and requires the intended new run action.
Boundary run
Persistent cause, moving load, active run command, communication loss, repeated reset, power cycle, local mode, STO state and fault-history rollover.
Injected fault
A process, supply, motor, parameter, drive protection, communication, PLC logic, reset, ready or restart mismatch.
Target check
The procedure verified with current manufacturer documentation, safeguarded load and site-approved reset and restart rules.
Should a PLC automatically reset every VFD fault?
No. Preserve the fault, identify the cause and define which faults and conditions permit a controlled reset. Repeated blind resets can damage equipment or create restart risk.
What must be true before resetting a drive?
Requirements commonly include cause removed, run request withdrawn, safe machine state, correct command source, drive available and authorized operator or sequence action.