Asset Management System - HART Compatibility with Field Devices


Thread Starter


I have a scenario, where My field Instruments are coming with HART V5.x.

On the other hand, the Asset Management System (AMS) is coming with HART V7.x.

Though the Control System supplier suggests its downward compatible. I am worried, if there can be compatibility issues related to TIME STAMPING?

Thanx is advance.
Emerson published a note on the HART 7 revisions that includes the major features of HART 5 and 6. of HART Revisions.pdf

According to that document, time stamps using the device's internal real-time clock are part of the HART 7 specification but were not part of HART 5 or 6.

I can not recall from my experience any HART 5 device that had a real-time clock capable of time stamps. I doubt any did, since there was no expectation of time stamps for HART 5 devices.

It seems from a quick read of one vendor's HART 7 implementation that time stamps are associated with events like "Read power fail counter and its time stamp" or "Read current and min operating voltage and its timestamp". I might have missed it, but I didn't find where time stamps are connected to reading variable(s).

If you need time stamps for HART 5 or 6 devices, I think that your 'host system' will have to provide time stamps on the received HART data.


Thanx Mr. David.

I went through & could not find time stamping defined in HART 5 protocol.

Since, all my SMART HART transmitters support HART 5, I am skeptical for the time stamping possibility as well as its resolution.

HART5 does not support time stamping. However, HART7 systems still work with HART5 devices

HART5 systems do not work with HART7 devices. Make sure to upgrade systems to HART7 if you use HART

HART7 time stamping is essentially only used for WirelessHART devices. Not for 4-20 mA/HART devices.


richard ramsey

Just read this on the web contradicting what you stated about compatibility of Hart 5 system and with Hart 7 device:

While this updating is going on, the vast majority of wired devices installed in user plants and available on the market today are built to the HART 5 standard. However, because all HART versions are backward compatible and interoperable with each other, the HART version is mostly transparent to the user. Each HART version builds on the functionality of the previous versions without taking anything away -- the functionality of HART 5 is included in HART 6; the functionality of HART 5 and HART 6 is included in HART 7. This backward / forward compatibility preserves investments of both users and manufacturers as it enables a HART 5 control system to communicate with a new HART 7 device the same as it communicates with a HART 5 device. It also means that control system built to the latest HART 7 standard can communicate with all versions of HART devices -- HART 5, HART 6 or HART 7.