The base unit is fitted with the T2550 PAC I/O controller modules plus additional I/O modules.
These modules plug onto terminal units, which provide the wiring interface between the plant or machine and the I/O modules.
Bases are available in 5 sizes to suit the number of modules required in a particular system.
Communication between the I/O modules and the processor is effected by the use of a passive internal module I/O bus running the width of the base.
Each module position is tracked separately for additional security during live replacement of I/O modules