The system variable

Cascade Connect: Version 4.0
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# 7.7. The system variable

Cascade Connect recognizes the `&system` tagname as a special variable. Whenever a message is sent to Cascade Connect using `&system` as the name of the data point, Cascade Connect passes the value of the point to the system topic of the DDE client you are using.

To state this another way - you can pass commands to your Windows client program from the data server if the Windows client program supports the system DDE topic.

Excel is one of the Windows client programs that supports the system topic. There are a wide number of commands that can be passed to Excel. Here are a few we have found:

System Function | System Command Format | Example
--- | --- | ---
Open a file | `[open(filename)]` | `[open("c:\data.xls")]`
Close current file | `[close]` | `[close]`
Print current file | `[print]` | `[print]`
New spreadsheet file | `[new]` | `[new]`

We suggest you look in the Excel help files for more information on how to use `&system` commands.

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