Emerson Exchange 365

EOIC setup for EtherNet/IP UCMM or Class 1 IO... to exchange data with a ControlLogix.

Given:  There are separate Status and Command arrays in a ControlLogix.

Can you send me a link that illustrates how to setup the EIOC to use UCMM to (1) read a Status array of 100 INTs or 50 REAL (2) write a Command array of 100 INTs or 50 REAL.

Can you send me a link that illustrates how to setup the EIOC to use Class I IO communications to (1) read a Status array of 100 INTs or 50 REAL (2) write a Command array of 100 INTs or 50 REAL.

pmhamilton

• 3 Mar 2020 10:16 PM
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2 Replies

• Andre Dicaire

  

  • 5 Mar 2020 7:05 PM

  The Class 1 Implicit communication is intended for simple devices that have defined instance assembly. I don't think this can be used with Array Tags in a PLC.
  
  UCMM uses the Logix Array tags. The LDT is pointed to the Logix Tag by name. The starting address is not configurable, so the LDT can map up to the first 100 registers in the array, regardless of data type. Different data types need separate Array tags and LDT's.
  
  A UCMM LDT can be used to both write and read data. However, the write is via Block write, which will send all values to the PLC, overwriting the data in the Array. To avoid data loss, the LDT had to read data faster than the DeltaV Modules write to it so DeltaV LDT registers update with PLC data between the cycles when it writes all data. You have to be careful that and data you read from the array will be continually updated, and not written as oneshot from the PLC. Otherwise, if the update coincides with a Write from DeltaV, the array register might be reset by DeltaV to the last value, and on the next read, DeltaV sees the value it wrote instead of the new value from the PLC. IF the PLC updates continually, this overwrite is corrected and read by DeltaV on the next LDT scan.
  
  If you separate all outputs and inputs in separate LDT's, the overwrite issue does not matter.
  
  We have also found that continuous writes from DeltaV to UCMM array should be done from a single DeltaV Module per LDT. When the Module writes to the LDT, the PDT aligns the LDT scan with the module so that the write will push down to the PLC quickly, within 50 ms. If you have many modules writing to the same LDT, this can disrupt normal traffic to the PLC. Manual changes however do not occur quickly. Since the write only transmit on a change, we can use a single LDT for outputs written to by multiple modules, but only if these writes are few and far between, i.e. operator actions, not control module calculations.
  
  I don't have any documentation to point you to, other than a recent KBA ( the number escapes me). You can find it on the Guardian website.

  Andre Dicaire

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• TreyB

  

  • 11 Jan 2024 4:41 PM

  In reply to Andre Dicaire:

  What would I enter for the rack and slot number?? I have a device (Protonode) that is using EIP tags but is not a PLC..

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