HART (“Highway Addressable Remote Transducer”)


HART (“Highway Addressable Remote Transducer”) is a communication protocol designed for industrial process measurement and control applications.

HART (“Highway Addressable Remote Transducer”)

HART is an open standard and vendor independent. Because of this, it is the world’s most broadly supported protocol for the process industry, with thousands of HART based products available from different vendors.

It’s called a hybrid protocol because it combines analogue and digital communication. It can communicate a single variable using a 4-20mA analogue signal while also communicating added information on a digital signal that is superimposed on the standard 4-20mA current loop.

Using an analogue signal, information is sent only one way, either from the device to the host (inputs) or from the host to the device (outputs). Digital information can travel in both directions using HART.

Traditional analogue devices communicate only a single process variable, and you typically have no easy way to tell if the information they’re sending is valid.

With HART, you will get the process variable – but other types of information too. Information items are standard in every HART device such as:

  • Device status and diagnostic alerts
  • Process variables and units
  • Loop current and percentage range
  • Basic configuration parameters
  • Manufacturer and device tag information