The number of inputs and outputs (IO’s) defining the exact size of PLC.
we can divide PLC types into:
Nano PLC : Nano-type PLC will be having nearly 15 IO points.
Micro PLC : Micro PLC will be having 20 to 32 IO points.
Small PLC : Small PLC having 32 to 128 IOs.
Medium PLC: Medium PLC will be having 64 to 1024 IOs.
Large PLC: Large PLC will be having 512 to 4096 IOs.
Very Large PLC:A very large PLC control system will be having more than 5000 IOs.