Expert’s answer: HART without 4-20 mA?

No, you can’t have a HART without 4-20 mA. The HART network depends on analog communication. You can read more about the protocol here.

When you have a multidrop network, the current stays in 4 mA. Thus, you might say that you don’t have the 4-20 mA modulation, because the current stays at 4 mA and the process information comes from the HART communication.

HART without 4-20 mA
HART communication (copyright HART Foundation)

With that in mind, you have other HART protocols that technically don’t have 4-20 mA. For example, wirelessHART and HART-IP. Both protocols are HART, but they provide digital communication based on wireless and Ethernet.

For more information, please check the list below:

Other resources that might interest you

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I have an AMS suite device manager, and I would like to know if can I use the Viator Bluetooth with my software? Do you know about that?

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HART device power supply
I have another question about HART communicators and devices. The question is: should we feed 24 VDC to a HART device only through a PLC/DCS or can we do it with an external power supply?

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