VFD Pump Control

[Banben]

I am currently using E&H flowmeter which talk to a 1756-IF6I module. But I couldn't see the HART feedback data. I am new. Anyone met this issue before?

 

[Tom Jenkins]

I think you need to work on your question a bit more to define your problem as it relates to pump control. You may want to check your part number: I don't think the 1756-IF6I is supposed to read HART.

 

[widelto]

That module is not designed for hart, you must use 1756-IF8H.
Though you do not have that module ther are some things you can do :
Please connect your hart modem to your flowmeter and find out what is the operation range, i.e. 4 mA= xxxx kg/hr and 20 mA=YYYY kg/hr or other units.
Then you can scale your module 1756-IF6I to use that range, from that point on you can try to use a totalizer based on 4-20 mA signal.

 

[Banben]

The module was selected by other electrical engineer. I asked him change to Hart module. But he said should work.

 

[widelto]

In fact the module will work, I mean, the module can measure your flow, but main hart capabilities will not appear.

 

[Banben]

May I ask what "main Hart capabilities" should have?

 

[Tom Jenkins]

You don't need Hart to measure flow. Hart is provided in the meter to allow remote scaling and diagnostics. If you had a Hart capable communicator or module you could get lots of info.

To measure flow, as Wedlto said, you just need the 4-20 mA analog output. In that case you can ignore Hart. Just treat it as a conventional flow transmitter.

 

[labeledas]

normally you would use hart for totalizers, but you can do this in the PLC as well. For flow rate the 4-20mA signal and has virtually no leg.

As stated earlier for HART you need and 1756-IF8H the IF8I cannot interpret the HART overlay signal at all, for the most part you don't really need anything from HART it is really just a luxury.

 

[Banben]

I got it working. Actually, we add a VFD to pump control. VFD is hardwire start / stop / speed reference / speed output back to PLC. I don't if how to change VFD speed. Can I use the flow meter input or need added other sensor like pressure transducer?

 

[Tom Jenkins]

First off, you seem to be in a little over your head. Can you get some guidance from the other electrical engineer? It might be a little more efficient than trying to get the help on line.

The answer to your question is probably "yes, you can use the flow meter". If you aren't sure about this you really need to get local guidance.