You will find all you need to know about HART here:
HART 5 is the most commonly used. Of the 30 million+ devices in the field, HART 5 accounts for more than 80 percent of them. HART 6 was only adopted by a few vendors. HART 7 is the current version, and it includes IEC62591-Wireless HART protocol. Since all HART versions are fully backward compatible, it doesn't matter which you use in the field, really. If you are building instruments, I strongly recommend doing that on the HART 7 platform. If you are an end user, I recommend that you only buy new instruments that are HART 7 compliant.
Editor in Chief
Control and ControlGlobal.com
555 W. Pierce Rd Suite 301
Itasca, IL 60143
I personally agree with Walt that most HART devices are version 5, and that the most important aspect of HART version 7 is WirelessHART.
For hardwired 4-20 mA devices there is not much difference between HART 5, 6, and 7. The speed is the same (1.2 kbit/s) so control is still done based on 4-20 mA. Many useful features in HART 7 like enhanced burst mode and time stamped reporting work best for WirelessHART which is faster (250 kbit/s) so I expect system will still use polling for diagnostics just like HART 5. Since two-wire loop powered devices must still operate on less than 4 mA, I expect the diagnostics to be the same too. So for 4-20 mA devices I think that HART 5 is OK.
Thanks to EDDL (www.eddl.org) intelligent device management software part of asset management systems are able to support hardwired HART version 5 (e.g. for the safety instrumented system) and WirelessHART version 7 (for monitoring) at the same time, and can also support Foundation fieldbus (for control) and PROFIBUS-DP (for drives) too. That is, there is no concern mixing versions.
> Does anyone know the pros and cons of the different HART versions, namely V5.X, V6.X and V7.X.
V7 includes all the required functionality of V6 which includes all the required functionality of V5.
One general comment is that V6 and V7 contains a lot of "Optional" functionality. If you see functionality you are specifically interested in you need to see if the functionality is "Required" or "Optional." If it is optional, you need to ensure that the host, communicator, calibrator, and the device both supports the functionality.
One specific comment is that V7 devices require V7 host, communicator, or calibrator to communicate. The initial communication message between device and host was changed in H7. H6 and H5 host do not recognize the new format.