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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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  • The point that I don't understand is why I don't see this speed difference when running very similar code in the Pcdmis scripting environment. Setting app.visible to false in VBA gave me the same speed as running with app visible in the pcdmis environment. What is the difference between Pcdmis scripting and VBA scripting other than the details of the language syntax?
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  • The point that I don't understand is why I don't see this speed difference when running very similar code in the Pcdmis scripting environment. Setting app.visible to false in VBA gave me the same speed as running with app visible in the pcdmis environment. What is the difference between Pcdmis scripting and VBA scripting other than the details of the language syntax?
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