Applies To:
  • CitectSCADA 5.00

The IOServer cache is not being updated correctly when a write is done to the PLC. This causes the value of the tag to toggle between old and new values just after it has been written to. 

CIT has confirmed this to be a problem in Citect for Windows version 5.00. This problem has been fixed in version 5.01.

You may work around this by disabling the cache on the I/O Server or make the cache time shorter than the page scan time. The page scan time defaults to 250ms and the cache time to 300 ms. By reducing the cache time to below 250ms or increasing the page scan time above 300 will resolve this problem.