Allen-Bradley · Logix 5000 Advanced Process Control and Drives
The command issued via a PCMD instruction to an equipment phase, or via an SCMD instruction to an equipment sequence, is not valid given its current operational state. For example, a START command is invalid if the equipment is already running.
Click steps to track your progress.
Review the current operational state of the equipment phase or sequence before issuing any commands.
Modify the control logic to ensure commands are only sent when the equipment phase or sequence is in a state where the command is valid (e.g., only send START if currently in STOPPED state).
For SCMD instructions, limit execution to a single scan using a P1 Pulse or one-shot, as commands are state-dependent and become invalid once the sequence state changes.