Applies To:
  • CitectSCADA 1.00 1.01 1.10 1.11 1.20 2.00 2.01

If Citect is communicating to one port of the Hitachi PLC and The PLC programming software is communicating to another port then if you try to do a "save to PLC" it will fail.  

When Citect is communicating with the PLC it takes a read token (or read occupation) from the CPU. When the programming software is requested to do a "save to PLC" it also needs this token but it will fail because Citect already has this token. the solution is to do a "Force free occupation" under "communication" in the programming software, then do the "Save to PLC". This will put Citect off line after about 30 seconds and then it will re-initialise and go back on line again. This is limitation of the Hitachi PLC.