TCPIP VISA source couldn't be found

[lvfanqie]

1. I run VISA Find Resource VI but couldn't see the resource for TCPIP which is actually there with my computer. I even could communicate with it. And also I couldn't see the list in Measurement&Automation utility.

2. Once I connect the Ethernet cable, the labview program will response very slow. If I disconnect the Ethernet cable, everything will be normal.

This is really bother me. Can somebody help?

Thanks a lot!

[smercurio_fc]

TCP/IP resources are not automatically added to MAX. Think about it. In order to do so MAX would effectively have to scan your entire subnet and do a poll for each possible address, with an associated timeout on each one, which is probably 1 or 2 seconds. Assuming just a class C network that's 255 addresses at 1 second each, which would mean MAX would take over 4 minutes to display the list. You can add TCP/IP resources to MAX and give them an alias and then they will automatically show up on a VISA resource name control.

Note that once you've initiated communication with a TCP/IP instrument using the VISA functions that resource should show up on the VISA resource name control for at least the duration that you keep LabVIEW open.

As for your other problem with the cable you will need to provide more details, like what your program is doing


Message Edited by smercurio_fc on 03-27-2008 01:24 PM

[Sputnikrent]

Hi lvfanqie,

smericurio_fc was exactly right in his explanations. There is a good KnowledgeBase article here that explains how you can add the TCP/IP resource to MAX.

Give us more detail about what your VI is trying to do so we can figure out why things slow down when you add an ethernet cable.

[lvfanqie]

Thank you for the reply. Now I could understand why MAX dosen't show the resource name for the TCPIP. But I still don't understand when I connect the ethernet cable, my labview program will hang and have very slow response(almost like a 'dead' program) until I disconnect the cable. The program I run is very simple just want to find all the resource in my computer and open a serial port resouce. I am using Labview7.1 and a cross-over ethernet cable.

[Sputnikrent]

Hi lvfanqie,

Is the LabVIEW VI that slows down when you plug in an ethernet cable the one you use to run the VISA Find Resource VI? If yes, the reason why the VI runs slowly might be because, like what smercurio_fc above said, it is scanning the entire subnet and polling each possible address, and it will have to timeout on each one.

Could you please give the expression you send as an input to the VISA Find Resource VI?

[lvfanqie]

Hi Rasheel,

Thanks for your reply. For Visa Find Resource VI, I use the default value as input (''?*"), which I want to find all the resource in my computer.

Actually, this slow down crash doesn't always happen. I tried about 5 times in same computer with same program, only 2 times my application got this 'no response' problem. If VISA resource always look for TCPIP and wait until timeout, I should get that problem everytime I ran my application, right?

Thank you very much for the support!

lvfanqie

[Sputnikrent]

In the 3 times that the program does not crash, how long does it take for VISA to find your device and your program to finish running? Does it take a long time also? Or does it execute really quickly?

Have you tried breaking your program down to see which part of it causes the slow down, or timeout? Try using highlight execution mode to see which VI it slows down at. Is there also an error message that is returned when the VI times out?

[lvfanqie]

The thing is I even didn't run the application and everything is so slow. For example, I switch front panel and back program. Once the ethernet cable is connect, the front panel will show up after 2~3 mins 'no response'. If I disconnect the ethernet cable, the front panel will show up right away.

[lvfanqie]

I use Windows Task Monitor to watch the process. I found once I connect the ethernet cable, the labview application will not responding from time to time. At this time I even didn't run the application and just open it.

[lvfanqie]

I found this problem only happen with laptop. It never happens in my desktop. Both of the computers have the same softwares(labview, MAX).

And in the desktop, I could see the TCPIP resource properly. But in laptop, even MAX successfully creat session for the TCPIP resource, I still couldn't see the resource name at the orgination tree. Please see the pics I attached.

Could it be possible I miss some drivers in my laptop?