Auto Detection of Cold Junction Compensation in a Temperature Module

An I/O module, comprising:

• a base configured to selectively receive either a first removable terminal block (RTB) or a second RTB;
• an I/O circuit mounted within the base;
• a plurality of first contacts mounted within the base and electrically connected to the I/O circuit;
• a first cold junction compensation (CJC) sensor mounted within the base proximate one of the plurality of first contacts and operative to generate a first feedback signal corresponding to a temperature present at the corresponding first contact;
• a controller in the I/O circuit operative to generate a control signal to selectively connect the first CJC sensor to an electrical ground connection;
• and
• a switch connected between the first CJC sensor and the electrical ground connection, wherein the switch receives the control signal to selectively connect the first CJC sensor to the electrical ground connection.

A method of detecting a cold junction compensation (CJC) sensor in an Input/Output (I/O) module, the method comprising the steps of:

• providing a first cold junction compensation (CJC) sensor proximate a second contact from a contact pair, wherein:
• a first contact of the contact pair is mounted in a removable terminal block (RTB) for the I/O module,
• the first contact is electrically connected to a terminal for the RTB,
• the second contact is mounted in a base for the I/O module, and
• the second contact is electrically connected to an I/O circuit mounted in the base;
• generating a first feedback signal with the first CJC, wherein the first feedback signal corresponds to a temperature present at the second contact;
• selectively connecting the first CJC to an electrical ground connection with a switch;
• and
• detecting a first value of the first feedback signal with an analog-to digital (A/D) converter, wherein the first value corresponds to the first CJC present in the base of the I/O module and the switch closed to connect the first CJC to the electrical ground connection.