Emerson Exchange 365

What is the best way to force a valve to CAS and OPEN?

I would like to keep as much of the logic in control studio the same, just incase they want things back to the original. I was thinking about just adding a CALC block, but I am unsure of what to actually do to make it easy for someone to troubleshoot and close the valve if need be. The operators will also NOT be able to change the Mode or SP. This is a standard OPEN/CLOSE valve. Can someone recommend a way to do this in a CALC block? I would like to keep the logic wiring if possible.

Lucky

• 28 May 2014 2:16 PM
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3 Replies

• Steve Elves

  

  • 28 May 2014 4:04 PM

  Your message is a little short on details, but in my opinion it is very dangerous to prevent operators from manipulating a piece of equipment, just in case there is an emergency of some sort.

   

  I would suggest instead that you leave the mode selection up to the operator, but configure the DC1 block so that the Normal and Target modes are CAS.  I would configure separate supervisory logic that drives the CAS setpoint of your valve module to the correct position to meet process conditions.

   

  If you are just going to have a valve that is always open and can't be manipulated by an operator, it's hard to see why you even need a DC block.

   

  Steve Elves

  Process Control Technologist

  ---

  From: Lucky [bounce-Lucky@community.emerson.com]
  Sent: Wednesday, May 28, 2014 7:16 AM
  To: DeltaV@community.emerson.com
  Subject: [EE365 DeltaV Track] What is the best way to force a valve to CAS and OPEN?
  
  

  I would like to keep as much of the logic in control studio the same, just incase they want things back to the original. I was thinking about just adding a CALC block, but I am unsure of what to actually do to make it easy for someone to troubleshoot and close the valve if need be. The operators will also NOT be able to change the Mode or SP. This is a standard OPEN/CLOSE valve. Can someone recommend a way to do this in a CALC block? I would like to keep the logic wiring if possible.

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• AdrianOffield

  

  • 29 May 2014 4:04 AM

  Modelock override is what we usually use, if the device is used in a sequence and you use equipment arbitration, you take ownership through a sequence and put the device mode to CAS.  If an operator should want to take back control, a tickbox appears on the faceplate to allow them to override the ownership, allowing them to put the device back in AUTO mode.

   

   

  From: Lucky [mailto:bounce-Lucky@community.emerson.com]
  Sent: Wednesday, May 28, 2014 5:17 PM
  To: DeltaV@community.emerson.com
  Subject: [EE365 DeltaV Track] What is the best way to force a valve to CAS and OPEN?

   

  I would like to keep as much of the logic in control studio the same, just incase they want things back to the original. I was thinking about just adding a CALC block, but I am unsure of what to actually do to make it easy for someone to troubleshoot and close the valve if need be. The operators will also NOT be able to change the Mode or SP. This is a standard OPEN/CLOSE valve. Can someone recommend a way to do this in a CALC block? I would like to keep the logic wiring if possible.

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• Devpriy sahu

  

  • 23 Dec 2017 4:47 AM

  In reply to AdrianOffield:

  Could you kindly explain little more on how ownership through a sequence is taken and valve in kept in cas mode.
  How it is coded in logic.

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