The PSD-120 is part of the Allen-Bradley Microtran series of programmable logic controllers (PLCs). It is a 120-point I/O station for distributed digital automation control. It features 24V DC inputs, 120V AC outputs, high-speed counters, and direct high-speed, programmable inputs and outputs. With this PLC, users can control process operations in various industrial applications, such as motor control, data collection, and machine control. It is modular and can be expanded up to 40 I/O points with the addition of PSD-20 I/O expansion units. It is highly reliable and offers reliable operation in extreme conditions. It has seamless communications with common industrial networks, and programming and software development is easily performed, making it a versatile and economical choice for industrial automation.