Emerson Exchange 365

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Writing to DST in another Controller

Hi All,

I am looking to have a landing module in one controller for profibus I/O that is physically located on another controller.

I am running DV version 12.3.1 on both controllers. When i try and write to an output parameter set as external reference, with external reference path set to the DST for the I/O, the value will not populate across. I seem to be able to receive data into the landing module from the external I/O DST's but not send.

Is this related to firmware on the I/O module? Controllers were upgraded to 12.3.1 but the I/O cards have not been done.

The landing module is assigned to the controller that does not contain the physical I/O. I have found that if i create an extra module and assign it to the controller that does contain the physical I/O and write to a input parameter within it and pass this to an output parameter with external reference set to the I/O DST the value is written to the I/O.

This is a work around but i thought it should be possible to write directly to the DST in the second controller.

Thanks

Tony_M

Tony_M

• 29 Sep 2014 10:47 PM
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2 Replies

• Ray Emerson

  

  • 29 Sep 2014 11:36 PM

  Hi, Tony. What you're trying to do is actually not permitted (i.e., write directly to I/O in one controller from a second controller). You could write to an input as whatever your source datatype is, and wire that to an output / internal write parameter that's tied to the DST.
  
  Functional, but there are a lot of potential failure modes and equipment / personnel safety issues to consider. I would definitely encourage you to think about possible failure cases, should the two controllers lose communications to one another. And, if at all possible, keep the continuous logic in the same controller as the I/O.

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• Tony_M

  

  • 30 Sep 2014 5:12 AM

  In reply to Ray Emerson:

  Thanks Ray
  I am aware of the failure modes and will address. I find it strange that it is not permitted. Other control systems i use can do this function with some status/ quality signal checks as it passes through. The situation i have is that from processes controlled in a controller in one locations needs to drive outputs in another location to activate relays. The controller at the destination is pretty full and i am trying to avoid adding load to it if i don't have to
  Tony M

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