The function of a transducer is to

A transducer is a device used to convert one form of energy or signal into another form. In the context of process control and instrumentation, the primary signal could be anything from pressure, temperature, flow rate, etc. The primary signal is typically in a non-electric form. The function of a transducer is to convert this primary signal into a more useful quantity, usually an electric impulse.

For example, a pressure transducer converts the pressure signal into an electric voltage signal, which can then be easily manipulated, processed, and transmitted to control systems or displays. Similarly, temperature transducers convert temperature signals into electric signals.

Therefore, the function of a transducer is to convert the primary signal into a more useful quantity, usually an electric impulse.