Emerson Exchange 365

DeltaV Modbus RS485 Connection to compressor showing intermittent device failure?

We have a Version 12 DeltaV system and we are trying to establish communication with an Atlas compressor. The communications coming off the compressor are CAN and going through and MK5 gateway to convert to Modbus RS485 communications (half duplex). We can use a ModScan program at the gateway and right before the DeltaV card and see the register values coming in and changing. However on the DeltaV Serial Card (S Series) and port, we are showing an intermittent "device failure" error show up in diagnostics. Everything seems to be mapped correctly, and we are asking for the right dataset types and registers. I have also tried to scale down the number of registers I am asking for (even down to one register) to see if I can clear the errors but I am having no luck. Has anyone else seen this type of issue on a Serial card talking Modbus through a gateway?

hnmcnabb

• 30 Jul 2015 11:44 PM
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4 Replies

• fairchdm

  

  • 5 Aug 2015 4:59 PM

  Are you sure you have the Register Offset Right? This can cause lots of trouble until you get it matched up. For analog Inputs my DeltaV uses floating point w/ status, PLC - Holding register has a base address of 40001, PLC register offset of 768, with 60 values. My DeltaV Addresses start at R40769 and proceed with R40771, R40773 until R40827. For Discrete input with status, PLC register is coils, Base Register address of 1, PLC Register Offset of 3072, with 11 values. My DeltaV Address starts at R3073 and proceeds to R3083. This was talking over a modem to a remote station PLC. Best of luck.

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• hnmcnabb

  

  • 5 Aug 2015 5:26 PM

  In reply to fairchdm:

  I am sure we have the right offset. I confirmed with the values coming in on the ModScan32 program. The values on those registers are what I am expecting and also the same as the ones I have set in my dataset

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• DBacker

  

  • 5 Aug 2015 5:40 PM

  I have configured an interface between an M-series DeltaV serial card and 2 different S-Series serial cards to an Atlas-Copco MkIV CAN to Modbus adapter. I got the M-series card to work just to prove concept. The actual project was S-series serial card. Check your hardware firmware revision level of the S-series serial card. This sounds crazy ( I'm now off the project so I don't have access to the cards), but the newer S-Series serial card firmware revision 14.x (I think), did not work with the MkIV adapter. Firmware revision 13.x (an older card bought out of the store room on site) worked. I believe people in Austin are looking into this. If you can get an "older-ish" S-Series card to borrow from your LBP or out of your store room, see if that works.

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• hnmcnabb

  

  • 5 Aug 2015 5:54 PM

  In reply to DBacker:

  Now that maybe something... we are using S-series with a HW Rev 44.7 and software revision 1.53.... I may need to make contact with my rep to see what the deal is! Thank you so very much!!!

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