CS1 series based on the river, has more than 200 different input and output units and represents the largest Omron's PLC series with a maximum capacity of 5,120 digital inputs / outputs. Up to 7 expansion racks can be connected to the CPU rack which allows the use of up to 80 input-output units. Any combination of digital, analog, and communication unit can be made regardless of the sequence. The huge instruction set and a large library of function blocks allow compact writing programs using a combination of STL and ladder language.