Schneider electric zelio extendable modular plcs schneider electric sr3b101fu this modular smart relay from the zelio logic series has 6x discrete inputs 4x relay outputs and a supply voltage of 100 to 240v ac the compact unit is designed for simple control systems and can have its functionality extended by the addition of separate io modules the units also comes with an internal clock and display the module can be din rail mounted and also has retractable lugs that enable screw fixing