VISA Performance

[task]

"I have two machines running the same program, interfacing with a serial device. Both are running Labview 6.1, NI-DAQ 6.9.3. The only difference is one machine is Windows NT, the other Win98. The Win98 machine runs the serial program about 3 times as slow. There is no difference in the program. Any clues?"

[Ray.R]

I wouldn't expect a speed difference because of the serial port. What about the performance of the different PCs? I suspect the Win-NT is more powerful. If so, it may be capable of doing the other tasks (non-serial communication) faster.

One bottleneck may be writing data to the HardDrive.

When you say they are the same, is all the hardware within the PC the same and the only difference is the OS?

[task]

The hardware is the same, the only difference is the operating systems. While I am performing the serial read/write, no other tasks are being performed...no writing to the hard drive, no user entry, no screen updates. That's why I'm stumped!!

[RobCole]

Having run LabVIEW on a variety of systems, I've found that it's not that unusual to find a program run faster on an NT system than on other systems. I haven't compared WIN2000 with NT yet, but WIN2000 does run faster than on XP.

NT has *MUCH* better multitasking than Win98, so this explains quite a bit. Those background tasks don't pull you down as badly. And, yes, there are always background tasks (such as updating the clock).

Rob

[Ben]

It looks like the others have given you some good ideas and explanations. The is only one thing that comes to mind.

Have you compared the VISA versions?

The were some performance enhancements implemented in one of the VISA updates.

Ben


Ben Rayner
Certified LabVIEW Developer
www.DSAutomation.com

[task]

The VISA versions are the same, 6.9.3 but I was going to update it to the latest 7.1. I forgot to mention that this machine used to run NT but the hard drive crashed so I had to replace it. I was having a hard time replacing the NT so in a crunch loaded Win98. If the customer can get some down time I want to reformat again and load NT. Very frustrating!! Thanks for everyone's help.

[Dan_Mondrik]

You're thinking of the *DAQ* version. The current version of NI-VISA is 3.0.1 on the Windows platforms. The version that came with LabVIEW 6.1 was NI-VISA 2.6.

Dan Mondrik
National Instruments