Bad Performance with NI-VISA and NI-488.2 under Win XP

[Michael Heimann]

I have an application (originally developed under LW/CVI 5.5.1), that use VISA for both, GPIB and serial communication. The application runs fine under NT 4.0 but under XP there are delays in conjunction with serial communication, which slow down the whole application. I already compiled the application with LW/CVI 6.0, installed NI-VISA V. 2.6.0 and NI-488.2 V. 2.0 but this didn't change anything. Do you have any ideas?

[Ray K]

Hello Michael,
We have noticed the reduction in system performance in Windows XP when multiple ports are installed, and large packets are being read/written at high baud rates (460.8k). Performance is acceptable when using smaller packet sizes or slower baud rates (115.2k for example). It appeared to be a bug in XP, because the problem was fixed when a prerelease version of XP service pack 1 was installed.

Regards,
Ray Kong
NI Applications Engineer