HART additional display


Thread Starter

Toni Kaesbeck

All: I am looking for a display unit, to be mounted outside (e.g. IP67), that can be put on an existing HART line and display the primary value, read by a HART master. This should be only in a kind of "listen mode". Configurable engineering units would be a plus. Does anybody know, if this is technically possible and if there are any products? Thanks, Toni Kaesbeck
There is a South African Company called Omniflex that manufactures Hart Modules and separate cost effective LCD operating panels that can easily be integrated. This person would be able to help you. Ian at [email protected]

Eric M. Klintworth

I'm anything but a Hart expert, but isn't the the "primary value" from a Hart transmitter sent out as a 4-20mA signal? I just installed a Hart pressure transmitter that is wired to a 4-20mA PLC input. It was set up with a Hart communicator (by the vendor), but there's nothing at the site that can talk Hart--the PLC just reads the 4-20 signal, just like it would from a dumb transmitter. If I'm right, all you need to display the primary value is a 4-20mA loop powered indicator. There are dozens of manufacturers, and certainly some IP67. Hart gurus, speak up! Eric M. Klintworth Sharp Technologies, Inc. Columbus, Ohio

Sztrancsik Csaba

Although I am not a guru, but as far as I know, you are right. A HART transmitter can be switched as a conventional 4-20 mAmp transmitter. That case you cannot use multiple devices on the same pair of wires, but still can use the HART modem signals /if you are having a suitable receiver/. The HART modem signals are figured out in a way, that (under a certain frequency) they do not interfere with the normal 4-20 mAmp signal. /Their average is zero./ To use more HART devices on the same loop, you must switch the address switches, give different /and non-zero/ addresses to the devices on the same loop. Than the devices will consume 4 mAmp each, and use only the HART protocol for operation. Regards, Csaba AtySoft Ltd., TEL: (+36 1) 316 3251 FAX: (+36 1) 212 0250