What is the difference between the read/write on RTE controllers and the read/writes on DMCplus controllers?

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Products: Aspen DMC3 Builder 
Last Updated: 01-May-2019
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Article ID: 000057023
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Problem Description
 
What is the difference between the read/write on RTE controllers and the read/writes on DMCplus controllers?
 
Solution
 
In the case of ACO based controllers there are different write lists for different types of parameters like AWRITE, PWRITE, WRITE and RDWRT. These amount to different I/O lists that are written by the controller process itself (control.exe). 
 
In the case of an RTE controller the I/O is not done by the controller process itself it is done by the RTEservice process. The controller process is separate from the I/O.  You can navigate to task manager and check that you have the RTEService.exe running and one RTEApplication.exe for each controller, below image shows a system with 5 RTE applications. The RTEservice writes a single list and reads a single list for each controller
 
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To configure the RTEService connections, go to Configure Online Server/ IO Tab, for each CIMIO type you will have an AspenTech.ACP.IO.CimioClientDriver.exe process running. Next image shows 4 cimio connections.
 
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Additionally, this read or write list could be broken up into multiple lists based on the IOSources defined and list size:
 
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While both controllers can use Cim-IO for performing I/O there are differences in the configuration and the error handling in the two controllers.  I/O write failures in an RTE controller will show up differently than I/O write failures in an ACO controller.
 
For an RTE controller it is useful to configure the read and write failure limit to specify controller behavior on read and write failures. V10 EP 12 has the option for write failure limit and V10 CP2 added the read failure limit:
https://esupport.aspentech.com/apex/S_SoftwareDeliveryDetail?id=a0e0B00000FJxfRQAT
 
To configure this setting go to the Deployment step/Online settings.
 
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For ACO based controllers I/O failures causes either missed cycles or controller turn off events and there was the WFAILM parameter to configure controller behavior on WRITE failures. Read Failures would cause missed cycles.
 
RTE controller I/O Read failures cause the controller to turn off due to invalid measurements inputs (For versions prior to V10 CP2). I/O Failure write failures are only acted upon if a write failure limit is exceeded.
 
The following KB explains how to read write error messages from the PCWS:
 
https://esupport.aspentech.com/S_Article?id=000033728
 
Keywords
 
DMC3 Builder
 
DMC3
 
Read Write
 
PCSPUT