PSSu BP-C1 1/12 S 312622 Carrier units for the I/O modules and supply voltage modules. These modules are simply inserted on to the base modules and are easy to change when making system adjustments. PSSu, base module for electronic modules, periphery, C-rail, 1-row, 6 connection levels, 12 terminals, screw connection. All the internal 7signals are present at the terminals!