(Mx4 I/O Expansion module for PLC applications) offers 128 user
I/Os (64 inputs and 64 outputs) on a single card.
Two Mx4 I/O expansion modules can be connected together to take full advantage
of the Mx4ís full 256 I/O capability. The Mx4 I/O Expansion module includes
two types of I/O interfacing connectors, opto-coupler compatible (Opto22,
Gordos-compatible) and high-density TTL for customized interfacing.