An RS-422A/485 Option Board can be mounted to an Option Board slot on
the CPU Unit. With a CPU Unit with 30, 40 or 60 I/O points, either Option
Board slot may be used.
When mounting an Option Board, first remove the slot cover. Grasp both of
the cover’s up/down lock levers at the same time to unlock the cover, and then
pull the cover out.
Then to mount the Option Board, check the alignment and firmly press it in
until it snaps into place.