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Why is writing to PC-DMIS from VBA so slow?

I have two scripts that do very similar things : Read scan point data from PC-DMIS and then write scan point data back into PC-DMIS. One version of the script is written and executed in PC-DMIS basic. The other is written in Excel VBA and is executed through Excel by calling the macro from a very simple PC-DMIS script.

The PC-DMIS only version writes the scan data out to a temp file and then reads it back out of the file and writes to PC-DMIS. The excel version reads the data out into memory in a 2D array and then writes it back into PC-DMIS from the array, no external files involved.

I figured the Excel version would be faster since everything is in memory. It turns out that it is wicked slow and takes about 11 seconds to write a 64 point scan while the PC-DMIS version does it in less than 1 second. All the time is in the writing via the Puttext method. Reading from PC-DMIS into the array takes a fraction of a second but writing it back out into PC-DMIS takes 11 seconds. In the PC-DMIS only version both operations take a fraction of a second.

Is VBA just inherently slow for this kind of thing? Anyone else experienced this?
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  • I've had up to an 8-fold increase in Excel VBA execution speed by using the Application.Visible property. Try setting it to FALSE before your main crunch then to TRUE when done. The PcDmis application window will minimize while FALSE. Thinking that updating the Edit Window was the slowdown I also tried EditWindow.Visible = (True/False) but didn't realize near the same speed gain as with Application.Visible. I'm sure the results can vary depending on what you are doing but in my cases it's become a go-to policy when I don't need to watch PcDmis update while the code is running.
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  • I've had up to an 8-fold increase in Excel VBA execution speed by using the Application.Visible property. Try setting it to FALSE before your main crunch then to TRUE when done. The PcDmis application window will minimize while FALSE. Thinking that updating the Edit Window was the slowdown I also tried EditWindow.Visible = (True/False) but didn't realize near the same speed gain as with Application.Visible. I'm sure the results can vary depending on what you are doing but in my cases it's become a go-to policy when I don't need to watch PcDmis update while the code is running.
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