Applies To:
  • CitectSCADA 5.20, 5.21, 5.30

Due to differences in the way the Citect compiler and the I/O Server optimise data requests, client requests for data from a remote I/O device may fail to be satisfied from the I/O Server data cache. This may cause some variable tags to display as #WAIT. 

A workaround for this problem is to reduce both the BIT_BLOCK and MAX_LENGTH entries in protdir.dbf for the protocol used by the remote I/O device to 8. This workaround may increase network traffic and consequently reduce performance on client workstations.

CIT has confirmed this to be a problem in Citect for Windows version 5.20 to 5.30. We are researching this problem and will post new information here as it becomes available.