Applies To:
  • CitectSCADA 3.xx, 4.xx, 5.XX
  • CitectHMI 3.xx, 4.xx, 5.XX
Summary:
I have been looking at my I/O Device caching and it does not appear to be working as I expected. I am seeing requests to the I/O Device when only half the cache time has expired. Is this an error? 

Solution:
This is correct behaviour. The I/O Device cache will service requests for the duration of the cache time, however, if a request is made for data that has been in the cache for more than half the cache time, then it will also refresh the cache by requesting the data from the I/O Device. 
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