Difference between Compact PLC and Modular PLC

When I started learning Programmable Logic Controller PLC programming, I found it very difficult to understand the actual difference between compact PLC and modular PLC.

In the modular PLC, one rack consists of nine or eighteen slots.

Out of 9th or 11th slots

• the power supply connects with the slot number-one,
• the central processing unit (CPU) is fixed in slot number two and
• the interface module is fixed in slot number three.

Remaining slot numbers fourth to eleventh is used for the input and output modules, signal module, a communication module, an interface module, a peripheral module, a function module, etc.

Mostly, modular type PLC is used in automation industries. The more different brands of modular PLC are available in the market with their manufactured brand.

Hopefully, this difference between compact PLC and modular PLC gives you a better understanding. If you have any point to discuss, feel free to write in the comment.