Terminal blocks provide screw terminations for field wiring. S-series I/O cards snap onto S-series terminal blocks. Set the key on the terminal block before installing the card on the terminal block.
Simplex terminal blocks can be installed in any slot on the 8-Wide I/O Carrier. Redundant terminal blocks occupy two slots and must be installed in slots 1 and 2, 3 and 4, 5 and 6, 7 and 8. That is, the lower slot in a redundant pair must be an odd number.