Assuming the update rate is sufficient:
Is it supported to use HART digital signals for control?
Is it supported to use HART digital signals for interlocking?
When you say "assuming the update rate is sufficient" you may also want to ponder, "is the update rate always the same"? So if a technician calls up a tag on AMS and the system labors to populate all the parameters, does the variable you're aiming to use continue to update at the same frequency? What if someone connects a handheld configurator / calibrator? Will your control loop or interlock tolerate a change in latency? Wired HART is also a relatively small amplitude signal, so the demands on your "physical layer" to be properly shielded / grounded will be greater than the purely 4-20 mA applications.
If you didn't see it in the related posts Jonas Berge has written a comprehensive guide for using HART on LinkedIn . . .
In reply to Mike Link:
Andre Dicaire
In reply to John Rezabek:
In reply to Brian Hrankowsky:
In reply to Andre Dicaire:
In reply to js:
From what I've read in Jonas Berge's guide "burst mode" only applies to WirelessHART?
"The triggered burst mode and event notification (sometimes referred to as report by exception) functions are intended for WirelessHART not for 4-20 mA/HART"
"Do not use burst communication for devices connected to a control system or multiplexer because the burst communication will cause diagnostics and auxiliary variable monitoring etc. to slow down. Burst communication may also cause many communication error alarms in the IDM software."
I've heard of configuring some function blocks to compare the HART PV to the mA loop, maybe generating a maintenance alert . . .
Radiometric applications are typically averaging over a few seconds anyhow - maybe you are fine with 5-10 second updates. I remember a paper presentation by Terry Blevins where he explored the tolerance of loops for variable latency - mostly with respect to wireless. But when your technician is pulling a signature from the transmitter it might have some affect.
I would tend to favor the analog loop since it updates multiple times a second. Not sure about CHARMs but I think the M-series AI cards are somewhere around 20x a second.
Cheers,
John