What is the relationship and difference between thermocouples and temperature transmitters?

A thermocouple is a primary component that is directly in contact with the temperature measuring medium, and its output is the measured electromotive force value (mv), which cannot directly show the temperature value of the substance.

The transmitter is to convert the electromotive force value into a 4-20mA signal value, which can be transmitted remotely and can also be directly connected to the meter head to display the temperature value on the spot!

In the industry, there are generally control systems, such as DCS systems, the field directly with thermocouples on the line, this conversion can be carried out in the DCS system.

There are also integrated temperature transmitters that combine thermocouples with transmitters. The appearance is similar to that of the ordinary thermocouple, below is the protective tube of the thermocouple, above is the junction box! It's just the device inside the junction box is different.