Schneider electric zelio compact plc modules schneider electric sr2 b121jd this zelio logic module is a compact smart relay designed for simple control systems the unit has 12 io 8x discrete inputs4x relay outputs and a supply voltage of 12v dc the module comes with a large lcd screen that makes the system easy to use and also has an internal clock the module is easy to install and program using either fbd or ladder and the zelio soft 2 programming software is intuitive to use zelio