# Hart Server and Advanced Hart Commands



## psgama (Oct 26, 2015)

Well, I learned something new over the week and I thought I'd share it with you all.

Sometimes Hart devices can be a PITA. The DDs in the hart communicator aren't complete, and don't allow some additional functionality, or some functionality in the DTM used in Pactware, Fieldcare, or the Rosemount Transmitter Interface software doesn't exit.

My example is the assignment of variables to the PV, SV, Tv, and QV in a Endress & Hauser Promass 83. This method can be used on a DVC6200 Positioner as well

At the factory, the process variables are assigned to the following device variables:

• Primary process variable (PV) → Mass flow
• Second process variable (SV) → Totalizer 1
• Third process variable (TV) → Density
• Fourth process variable (FV) → Temperature

But what if your plant has a different standard and requires Volumetric Flow over Hart, which the materials team didn't handle? (Do they ever get anything right????)

Well, you can use Hart Server from the Hart Foundation and a Hart modem to send a custom command to change the variable assignment which is very similar to modbus!
Consult your manufacturer for the variable list or experiment by sending random numbers to the QV assignment.

For a Promass 83 these variables are:
0 OFF (unassigned)
2 Mass flow 
5 Volume flow 
6 Corrected volume flow 
7 Density 
8 Reference density 
9 Temperature 
And many more that I won't post. 

Just remember to convert the variables from decimal to HEX and away you go!

Neat little trick that I've never seen utilized in my 11 years in the E&I trade, so I thought I'd share


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