Visa Property node "intf inst name" return wrong names on NT

[Fehri]

Need to identify the common names of the usable serial interfaces on a computer. I use Visa Find resources, then make a type cast to be able to use the property node on the port references with read "intf inst name". I get COM1 and 3 times COM2 as response though I have ASRL1, ASRL2, ASRL3, ASRL4 from Find Resources.
Same application works fine on 2000 and 98 (here after update from VISA 2.6.1 to 3.0.1, before same problem) but does not work on NT(SP6).

[JDesRosier]

Hello Fehri,

This problem with NI-VISA in NT was apparent in previous releases of VISA, but this problem should not be present in version 3.0.1.

Have you tried to install NI-VISA 3.0.1 on the NT machine? I understand you did so on the 2000 and 98 machines. If you have not yet upgraded on the NT machine, I recommend you do so and see if this problem still exists.

I hope this helps. I will work with you until we have this problem resolved.

Best Regards,

Joe Des Rosier
National Instruments

[Fehri]

Hi Joe,

thanks for your response.
Yes, I have used same file (visa301runtime.exe) to install NI-VISA on each of the OS versions.

I have found a hint, that program will work more stable with use of VISA OPEN first and then use the property node. But problem with recognizing wrong ASRLs still exist.

Meanwhile I found out that even though VISA Find Resource tells me a presence of ASRL1,2,3,4 (same with downloaded NI example "Find_serial_ports.vi"), there are only COM1 and COM2 available on the computer.
So I get an error (-1073807360) when using VISA OPEN with ASRL3 and 4. When connecting this error output to Property Node, no "Intf Inst Name" is given anymore for ASRL3 and ASRL4. That's the way I can find out if interface is valid or not.

I hope
this works on other customer computers, too! Therefore this solution is not completely satisfying because "Find resource" identifies more ASRLs than really valid or available.

Best regards

Fehri

[JDesRosier]

Fehri-

Ok, let�s try the following:

First, try adding �::INSTR� (without the quotations) to your VISA commands, so that the command for ASRL appears as �ASRL1::INSTR�. Repeat this addition for ASRL1, ASRL2, ASRL3, and ASRL4 depending on which instruments you wish to read data from in your LabVIEW VI.

If this fails to correct your problem, please follow the instructions in the link below to properly change the address names (alias�) for each instrument.

Instrument Alias Change within MAX (NI Measurement & Automation Explorer)

Once you change the instrument alias within MAX, you can simply call it by the respective name in LabVIE
W, simplifying the code. For example, device ASRL1::INSTR can be renamed to �thermocouple1� and called by �thermocouple1� in LabVIEW. This nomenclature is a bit more intuitive if other people will be reading/modifying your code in the future.

I hope this solves your problem! Please let me know if you need further assistance. Have a great day.

Best Regards,

Joe Des Rosier
National Instruments