A Dew point meter is needed in every plant which has air operated instruments. Some instrument engineers selecting dew point transmitters to monitor the dew point temperature from SCADA.
If you have read the active and passive instruments article, you might realize that the dew point meter/ transmitter is an active instrument so you need to prepare the interface to connect the signal to controller’s I/O.
There are many brands available on the market, below is a figure of a dew point transmitter from cs instruments which has active 4-20mA output. Or it can be used as a local meter or gauge only by not connected the output signal to a controller.