Has anyone used 4-20ma HART valve controllers for open/close valves and how did you configure it in DeltaV utilizing a DC block or other?
We are looking to move away from bus and using CHARMS and we feel that the 4-20ma HART valve controller can provide us some benefits not achieved with DI/DO. Benefits: detailed valve position feedback, enhanced diagnostics, remote configuration, reduced wiring complexity, and the ability to monitor additional process parameters beyond just the valve position all while utilizing the established 4-20mA current loop standard for reliable signal transmission.
Curious if others have used and are those benefits realistic and how did you configure it in DeltaV.
Thanks
We use a 4-20mA controller on Open/Close Butterfly valves for some of our water valves. This is so that we can do water pushes at 25% open for a lower flow rate, and water cuts at 100% for a higher flow rate.
We use our standard valve DC Block that we use with all our open/close valves in the VALVE control module. Then we use an AO block in a second VALVE_OUT control module with a CALC block that sets the OUT.
IF '^/VALVE_SP.CV' = 1 THEN IF '^/WATER_PUSH.CV' = 1 THEN '^/AO1/MODE.TARGET' := AUTO; '^/AO1/SP.CV' := '^/H2O_PUSH_OUT.CV'; ELSE '^/AO1/MODE.TARGET' := AUTO; '^/AO1/SP.CV' :='^/H2O_CUT_OUT.CV'; ENDIF; ELSE '^/AO1/MODE.TARGET' := MAN; '^/AO1/OUT.CV' := 0; ENDIF;
I am sure theses could be combined into one control module, this is just how the guy before me set them up so that is what we do.
So in the equipment module the VALVE control module gets set to open and the ALVE_OUT control module gets set to a SP of Water push = 1 or 0
We are not using the feedback in this case but I think it could be done in a similar way.
I am sure there are other ways to do this, but I hope this helps.
In reply to Scott Dewar:
The SG9000 is exactly what we are looking at. Do you use the position feedback and determine a closed limti and open limit and feed that to the DC? We noticed that you can set limits for open close in the SG9000 and we are concerned about setting different limits within the module for open close.. Is the feedback a HART alarm or how does that work? Curious how you manage configure the feedback since there are limits defined in the valve for open and close and how you get that to line up?
How has the reliability of the SG9000 been for you?
In reply to Verx:
Yes we use the position feedback via hart to determine a close and open limit and feed that to the DC. Not sure if the images below will go through or not. The AO blocks readback is the hart_sv. That is then feed into our READBACK_CONV block that then ties back into the DC's F_IN_D1 and 2 inputs.
In here we comparator blocks, if the readback is less than 3 we consider it closed and if it is open more than 90 we consider it open.
The reliability of the SG9000's have been very good. First major project with many of them was in 2016.
In reply to KWIN JIANG:
In reply to Mark Bendele: