Expansion module of programmable logic controller

An expansion module of a programmable logic controller, the expansion module comprising:

• a function body comprising a housing, a circuit board and a first connector, wherein the circuit board is disposed in the housing, and the first connector is connected with the circuit board and is partially exposed from the housing;
• and
• an expansion base detachably assembled with the function body, the expansion base comprising:
• a bracket comprising a first sidewall and a second sidewall opposite to the first sidewall, wherein the first sidewall comprises a first opening, and the second sidewall comprises a second opening;
• and
• a three-way connector detachably disposed in the bracket and comprising a first conducting terminal, a second conducting terminal and a third conducting terminal, wherein the first conducting terminal is at least partially exposed from the bracket through the first opening, the second conducting terminal is at least partially exposed from the bracket through the second opening, and the third conducting terminal is configured to connect with the first connector,
• wherein when there are plural expansion modules, two adjacent function bodies can be detachably assembled with each other, and two adjacent expansion bases can be detachably assembled with each other.