Why is a HART function required for the transmitter?
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General design requirements specify that transmitters, valve positioners, etc. should operate on a 4–20 mA signal with HART functionality. What is the purpose of requiring HART? Is it just to adjust the time using a handheld device? How can loop testing be carried out without HART? Additionally, can HART also be combined with HART-compatible cards to read information transmitted via HART into the DCS?
The general reason for including HART is to facilitate the tuning and maintenance of the instrument in future use. HART is a universal protocol; in theory, instruments that support this protocol can all be debugged and maintained using a handheld programmer. A signal generator or multimeter can be used to test the channels. HART can be used in conjunction with HART-capable cards at the terminal to read information transmitted via HART into the DCS.
HART instruments can be easily integrated into DCS systems, and they can also work in conjunction with other control devices that are not part of a DCS or PLC system； HART instruments can be easily operated using a handheld controller.
How troublesome is it to operate on the on-site panel, compared to how convenient it is to retrieve information or make configurations directly on a computer or a handheld controller?
If all field transmitters, mass flow meters, intelligent valve positioners, radar or ultrasonic instruments, etc., are equipped with the HART protocol, then a single 475 communicator is sufficient for their calibration. Otherwise, one has to go to the device to calibrate the instruments; each instrument may have its own operator, so it’s necessary to bring several of them, which is very troublesome
The Hart protocol and Brown protocol are two common protocols that facilitate tuning; they can be installed after the disk is in place. Devices that support these respective protocols can be tuned directly using a handheld controller
Support – when purchasing the instrument, make sure it has HART protocol support.
It’s all for ease of use – the handheld controller or card inserter
How can a watch without a Hart perform a loop check? Not answered yet