A modern PLC manufactured by Siemens appears in this next photograph, an S7-300, which is a different design of modular PLC. Instead of individual cards plugging into a rack, this modular PLC design uses individual modules plugging into each other on their sides to form a wider unit:
![](https://i0.wp.com/www.electricalengineering.xyz/wp-content/uploads/2022/12/plc-type-5.jpg?resize=825%2C549&ssl=1)