Serial VI blocks command from an open pipe in linux labview.

[saltamontes]

For labview 8 professional in linux suse 10.0, I have the following problem:
For the open pipe in attatchment caso1.jpg, I get as expected, xmgrace running.
Adding a serial VI as seen in the  attachment caso2.jpg , xmgrace does not run  but no error is
reported by labview.
Somebody can help me indicating where is the mistake?
Thanks: Saltamontes.

[MichaelChaney]

A couple of things to note:

1) Be sure to include at lease simple error handling to notify you of any errors.
2) Since there is no data dependency between the pipe and serial functions, try using sequence structure to force one to occur before the other.

I've attached a screen shot in which I was able to successfully replicate this.  Remember that the Mode parameter is required for the command pipe VI.  In my code I placed a pause in between the pipe open and close functions and was able to check manually to see if More was running.  You might try something similar with your app.

[saltamontes]

Dear Michael:
Thanks for your help.
I have reproduced exactly the VI shown in your screen shot. Without the serial VI the pipe runs "more"
as expected, but when the serial VI is added, "more"  does not run since it is not listed with "ps -a". No
error is reported.
Still more, after deleting the serial VI an running  the pipe alone, "more" does not run.  To get running
"more" I need to close labview and reopen it and rerun the pipe alone, then I get "more" running.
I am including in the atachment a copy of my VI  where "more" does not run. I think it is the same as
in your screen shot.
 Do you have some suggestion where to look to remove the problem?
Thanks: Saltamontes.

[MichaelChaney]

Have you tested just the serial port by itself, without the pipe code?  Make sure that you can communicate with the serial port and that the serial driver for linux is properly associated.  In essence, make sure ASRL1::INSTR is a valid resource.  You can use a loopback test with the Basic Serial Read and Write example from the NI Example Finder under the Help menu.  Here's some more info about how to setup the hardware:

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000YFtECAW&l=en-US

It sounds like the serial code is the problem, and we need to make sure that is working properly first.

[saltamontes]

Dear Michael:
Indeed, I forgot to mention that serial port is fully operational.
In fact, I noticed the problem for first time, in an application that is using the serial
port, sending and receiving messages without problem. When I added the pipe
to this application  I noticed that the  command in pipe is not executed.
Thanks:  Saltamontes.
 
  

[MichaelChaney]

After reading back through your original post I noticed that you are using SUSE 10.0.  While LabVIEW is supported on this distribution, NI-VISA is not.  NI-VISA is the driver used for serial communication.  Here's a link to the current version of NI-VISA:

https://www.ni.com/en/support/downloads/drivers/download.ni-visa.html

The last version of SUSE that is supported by this driver is 9.3.  I was able to confirm that there are known issues with NI-VISA and SUSE 10.0, which is why it is not officially supported.

[Shawn B.]

Saltamontes,

Michael is right, there are some known issues with SUSE Linux 10.0 that we are currently working on.  It also appears that you have found one of them, but luckily there is a workaround as long as you aren't using VISA for PXI/PCI communication.  Here is what you need to do:

1.  Run visaconf
2.  On the Passports tab uncheck the "libnivipxi.so - NI-VISA Passport for PXI/PCI"
3.  Close visaconf and run your VI it should now work as expected

Shawn B.
National Instruments

[saltamontes]

Dear Shawn B.:
Thanks for the suggestion but for now I cannot test it since I have switched inmediately to SUSE 9.3. Besides, I am also using PXI communication.
I have tested the problematic VI in SUSE 9.3 where the problem is gone.
I will be attentive to your release for SUSE 10.0
Thanks: Saltamontes.