Applies To:
  • CitectSCADA 5.xx
Summary:
I am using the DDEDRV protocol to communicate with an Excel workbook. I have defined a variable tag in Citect with an address of "A1". However at runtime the value being displayed on my page is toggling between random values such as 0 and -142876. The correct value of cell A1 is not being displayed.  

Solution:
Referencing cells by the notation "A1", "A2", "B1".. etc. is not supported. You must use Row and Column notation such as R1C1. The Excel Workbook must also be set to use the same Row and Column notation. To do this go to the Excel Tools | Options menu item and select the General tab and modify the appropriate setting. 
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