Industrial Engineer · phase 1 of 16
Local I/O
I/O installed in the same rack or local assembly as the controller.
The Explain card
- Plain English
- Local I/O sits in the same rack as the CPU, or bolted right beside it. It talks over the backplane rather than over a network.
- Example
- The pushbuttons and pilot lights on the main panel door land on cards in the controller's own rack.
- Why it matters
- Local points update every scan with no network delay and no cable to lose. They are also the points you cannot move without moving the controller, so the choice between local and remote is a layout choice as much as a wiring one.
- Hook
- If you can touch the CPU and the card at the same time, that is local.
Where it sits in the deck
Phase 1: PLC Controller Hardware
The box itself, from processor and rack to the modules that plug into it, because nothing else in the deck lands until you know what a PLC physically is.
