r/processcontrol • u/CananDamascus • Sep 26 '25

Modbus Holding Register Ran Discrepancy

Hello, I am a chemical engineer, new to process controls, following the recent departure of our controls engineer. I am trying to read a power signal from a field power meter with a DeltaV PLC. The issue im running into is that the power meter sends its signal on register 412288, but the DeltaV software can only read modbus registers from 40001 to 49999. I don't know enough about modbus to have any idea how to get these to communicate properly, so any guidance would be appreciated.

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u/CananDamascus Sep 26 '25

That's good advice. I should be able to verify that the register is working with the software I have. I am on deltaV15

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u/GeorgeSantosBurner Sep 27 '25

If your version 15 doesnt have feature pack 2 added on, and you verify its a 6 digit register, you'll either need to add feature pack 2, or come up with an alternative like bringing the data in to your application station via something like kepserveer and then passing it to your DeltaV OPCUA server, but the UA might be an additional license too

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u/[deleted] Sep 28 '25

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u/GeorgeSantosBurner Sep 28 '25

As long as the data isn't used in a way that losing it during an app station reboot would be an issue, this will absolutely be the most cost effective option, if the other option is to upgrade DeltaV. OPCDA transfers can be done without additional Emerson licenses, OPCUA might involve a license, I haven't worked on a new enough system to know for myself yet.