The Siemens S7-200 SMART ST20 is a compact and reliable micro PLC ideal for small to medium automation systems. It features a 24 VDC power supply, 18 digital inputs, and 12 transistor outputs. As a transistor-output model, it is best suited for applications requiring fast switching and long operational life, such as high-speed counting or controlling solid-state devices. The ST30 is equipped with an integrated RS-485 communication port and a PROFINET/Ethernet interface, enabling easy networking and data exchange in distributed systems.

With a program memory of approximately 30 KB, the ST30 is capable of handling various automation logic, motion sequences, and basic control applications. It supports fast instruction execution, typically 0.15 μs for bit operations and 1.2 μs for word-level instructions. The micro SD slot allows for easy program backup and firmware updates. It also supports signal board extensions for analog input/output and communication expansion. The ST30 is widely used in conveyor systems, packaging machines, small assembly lines, and panel manufacturing setups.