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Endress + Hauser, Profibus DP, MYCOM CPM 153 PA how to write values?

hi,

I am able to communicate with Mycom CPM 153 PA and able to read all inputs from transmitter but when i am trying to write from Control module not able ?

Please help.

Hemant ikhar

• 25 Jan 2016 12:31 PM
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8 Replies

• Andre Dicaire

  

  • 25 Jan 2016 12:58 PM

  Verify mode of block and status of parameter. If you have not done so, set the status of the variable to 128 (Good). With DeltaV you have to map the status to a separate byte parameter.
  
  I found I had to do this with a DP/PA DVC before it would accept a setpoint write.

  Andre Dicaire

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• chip.burge

  

  • 25 Jan 2016 1:27 PM

  Make sure that the control module that is doing the writing is assigned to the same controller as your Profibus card. That would explain the ability to read but not write.

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• Hemant ikhar

  

  • 28 Jan 2016 6:04 AM

  In reply to chip.burge:

  We have assigned it to proper controller, same controller where we have connected profibus card.
  We have created single control module for read & write .

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• Hemant ikhar

  

  • 28 Jan 2016 6:42 AM

  In reply to Andre Dicaire:

  We have connected input Boolean parameters to BFi block, and changing values of these parameters to 1 / 0 through online control studio view.
  so status must be good .

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• Andre Dicaire

  

  • 28 Jan 2016 3:09 PM

  In reply to Hemant ikhar:

  I don't know what you mean in the above message.
  
  Profibus PA is similar to Foundation Fieldbus in that parameters also have a status Byte. The mapping of the status byte is similar to FF, with status, substatus and limit bits. Substatus values differ in some cases. So a Status of GOOD is 10000000, or 128 decimal. Unlike FF, where a parameter has both a .CV and .ST field, with Profibus PA, the status parameter must be mapped separately with DeltaV into two signals, say Param_Value and Param_Status. When you read these in DeltaV, they are both read with the .CV field. the .ST field on these parameters will reflect the health of the DeltaV signal, but the status of the parameter in the PA device is in the second signal.
  
  So if you want to write to a parameter in the PA device, you must map both the parameter and its status to signals, and confirm that the status of the parameter in the PA device is GOOD. If it is not GOOD, then write to this status a value of 128. If the value for status holds at GOOD, then the write should work. If the status does not hold, the device has a reason for not being GOOD, and is telling you something is wrong. The status value may hold the answer in the substatus portion of the status word, such as "Invalid MODE" or something else. If the block is in the wrong mode, writing to its SP would not be permitted. This is what happened to me when using a DVC6000 PA. The AO block was not in AUTO and the status was BAD (I forget the value). I was able to resolve the mode, but I also had to write the status to GOOD before I could write successfully to the SP of the block. I later found that on a power cycle, the Status would be BAD until I set it to GOOD. So I added the Status signal to my module and would set this to GOOD if it every went to BAD.
  
  My point is you have to check status of the parameter in the device, not status of the DeltaV module parameters. And the status at the device must be mapped through a separate Signal and read as a value (.CV) not the status field (.ST).

  Andre Dicaire

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• Hemant ikhar

  

  • 29 Jan 2016 1:06 PM

  In reply to Andre Dicaire:

  CPC 30 profibus manual.pdf

  Status is also good,

  In attached manual Pg no 15. Control CPC (SP_D),

  We are able to write 0000 0001 in Control CPC (SP_D), and it gets reflected in deltav Diagnostics that value of signal is decimal 1.

  We are able to write 0000 0010 in Control CPC (SP_D), and it gets reflected in deltav Diagnostics that value of signal is decimal 2 .

  But the PH assembly does not move to Measure Position & Service position.

  Do I need to send some more values to CPM 153 through Control CPC (SP_D) or do  i have to enable some other bits so that  PH assembly will start moving?

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• Andre Dicaire

  

  • 29 Jan 2016 4:34 PM

  In reply to Hemant ikhar:

  Hermant, I am not familiar with this particular device, so I cannot speak to what needs to be written to get the assembly to move.

  Andre Dicaire

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• Hemant ikhar

  

  • 30 Jan 2016 2:45 AM

  In reply to Andre Dicaire:

  thanks Andre for your support.

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