On most PLC units a terminal assembly is attached to the input/output cards. The terminal assembly is a terminal block that connects directly to the cards.
The terminal assembly simplifies connecting the field wiring to the input/output cards.
The terminal assembly also aids in troubleshooting and shortens the time required for replacing a faulty input or output card.
Usually, the terminal assembly will simply snap off of the input or output card. The card can then be replaced. Then snap the terminal assembly on to the new module.
This saves time in industry by the technician not having to unwire and rewire the module. The terminal assembly simplifies the job at hand.