They may include opto-isolation and different voltage levels.
Shown here is the EX233 termination panel which is designed for use with our PCI272 72 channel digital I/O board, or our PCI215 Counter/timer and digital I/O board.
The EX230 provides isolation for 24 digital input signals, and may be used with the EX233 termination panel or a PCI236 digital I/O board.
The EX213 is a 24 channel relay / isolated output board that may be used with the EX233 termination panel or a PCI236 digital I/O board.
For further details on wiring and configuration of these termination and isolation panels, please see the data sheet or contact our sales engineers.