RS232 comms problem between VB5 and VB6

I have an old VB5 application running on a Win98 machine that needs to
be ported to an XP machine running VB6.

The original application is used to calibrate an industrial hardware
product, and has 4 devices connected to the PC via RS232 serial ports.
The VB communications is handled via the MSCOMM control.

I ported the project to the new PC and opened the project in VB6, then
tried to run it from within the VB application. None of the devices
responded to the startup code.

I started to try to debug each device individually, by writing
separate little apps that address only a single device, and have had
"some" luck: I actually got one of the devices talking properly, but I
am having weird problems with the others.

For example, with another device, a digital multimeter (DMM), I have
had the following weirdness: I wrote an app the sends the Reset, Set
Remote, Test, and ID functions, each tied to separate command buttons,
then started playing with timing, etc, and I finally got it talking to
the DMM, but each button has to be clicked twice in order to get a
response. When I port the same app back to the old machine and VB5, it
works flawlessly!

I really need some help here, so please contribute any ideas you may
have.

TIA

JL

.

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