ENGINEERING NOTE
PLC-5 / SLC-500 modernization:
the first 10 checks
I/O, network, HMI, drives, safety, shutdown and testing checkpoints in legacy PLC modernization.
Control checkpoints
- Verify the installed base and catalog numbers.
- Extract I/O types, signal levels and field wiring.
- Record network protocols (DH+, RIO, Profibus) and node behavior.
- Define the HMI/SCADA tag, alarm and recipe scope.
- Check motor/feedback compatibility on drive and motion axes.
- Validate the safety chain separately.
- Define the capacity and expansion headroom of the new architecture (ControlLogix / CompactLogix).
- Prepare the offline conversion and FAT plan.
- Build the shutdown cutover sequence.
- Define rollback, commissioning and documentation criteria.