OPC/DDE server Frequently Asked Questions
OPC/DDE server Frequently Asked Questions
| Question | Attempting event-based data logging with DSDATA. When Excel cell data changes, I want to start data logging. Can you offer any hints? |
| Answer | There are two types of cell data changes (1) Editing the cell; (2) Non-editing cell data change. (1) EDITING THE CELL - If the cell data changes based on an Excel edit, then Excel has a Visual Basic subroutine called "Worksheet_Change" that gets executed every time an edit occurs in Excel. 1. Select Tools --> Macro --> Visual Basic Editor. 2. In the “Project – VBAProject” window at left, double-click on “Sheet1 (Sheet1)” to open it up. 3. In the “General” combo box at the top left of this now open Sheet1, select “Worksheet.” 4. In the combo box at the top right select the subroutine called “Change.” 5. Now enter this sample code: Private Sub Worksheet_Change(ByVal Target As Range) Dim cell As Range For Each cell In Target.Cells If cell.Row = 1 And cell.Column = 1 Then MsgBox "cell changed to " & cell.Value End If Next cell End Sub 6. After entering the code, then, of course save it. 7. Switch back to the Worksheet view (normal Excel view). 8. Now if you edit Cell A1, you will get a message box (e.g. “cell changed to ”). This is just a sample. It is used to fire up a message box, but it could be used to execute a macro. (2) NON-EDITING CELL DATA CHANGE - If the cell data changes based on something other than an Excel edit (e.g. macro changes it; value read from PLC changes it) then Excel has a Visual Basic subroutine called "Worksheet_Calculate" that gets executed every time Excel recalculates all its formulas: 1. Select Tools --> Macro --> Visual Basic Editor 2. In the “Project – VBAProject” window at left, double-click on “Sheet1 (Sheet1)” to open it up. 3. In the “General” combo box at the top left of this now open Sheet1, select “Worksheet.” 4. In the combo box at the top right select the subroutine called “Caculate.” 5. Now enter this sample code: Private Sub Worksheet_Calculate() MsgBox "cell changed to " & Cells(1, 1).Value End Sub 6. After entering the code, then, of course save it. 7. Switch back to the Worksheet view (normal Excel view). 8. Now if the data in Cell A1 changes, you will get a message box (e.g. “cell changed to ”). This, too, is just a sample. It is used to fire up a message box, but it could be used to execute a macro. |
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This item was last updated on 08-28-2003
Document ID: 959
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