(Engine-Level Function)
| Description: | Returns the value of the data for a specific item from a DDE server program. This function is a DDE client. |
| Returns: | Varies |
Usage:  |
Steady State only. |
| Function Groups: | DDE |
| Related to: | DDEPoke | DDEShareAdd | DDEShareDel | SetDDEServer |
| Format: |
DDE(Program, Topic, Item[, Error, Trigger, pollTimeOut]) |
| Parameters: |
| Program |
|
Required. Any text expression giving the name of the program which is the DDE server. This does not contain the .EXE extension. This is usually the same as the root file name of the executable file, but may be different as in the case of Microsoft Word for Windows 6.0 which uses the name "MSWord". |
| Topic |
|
Required. Any text expression giving the DDE topic name within the server. For a VTScada server the topic name is usually the name of the window. For Microsoft Excel, the topic is the spreadsheet name. |
| Item |
| Required. Any text expression giving the location or name of the value to retrieve. |
| Error |
| Optional. A variable that will be set when an error occurs. Values may be as follows: 0=OK, -1=DDE is stopping, -2=FAILED |
| Trigger |
| Optional. If present, this indicates a "COLD" link as opposed to a "HOT" link (i.e. you have to poll the server to get an update, rather than it pushing updates to you). When set to 1, this triggers a poll. The trigger is then reset. |
| pollTimeOut |
| Optional. If this is a COLD link (see Trigger) then pollTimeOut is the value in seconds of the time out for the poll. |
| Comments: |
VTScada DDE functionality is deprecated as of version 12.0.00 and should not be used in new applications. Extreme care is advised for its continued use. Special configuration is required to run, please reference Use VTScada as a DDE Server. This sets up a DDE client. After the link is established, the return value of the function will change whenever the value in the DDE server changes. |
Example:
cellValue = DDE("Excel", "Sheet1", "R1C1");
Upon execution of this statement, cellValue will contain the value of the cell in row 1, column 1 of the Excel spreadsheet called "Sheet1".
