Why don't I get viIn16 and viOut16 errors when the hardware is off?

[Believer]

I have a VXI chassis with some register based cards. The slot 0 is a MXI-2.

However, with the power off to the chassis, I can do the usual commands:

viFindRsrc, viOut16 and viIn16

and find the instruments and read and write to the registers - all without any errors.

So it seems that the info is being cached somewhere.

How can I avoid this and get true results when there is no power?

[Ebele_Obijiofor]

Hello,

When you call viFindRsrc, it simply looks at the Resman output table(C:\nivxi\tbl\resman.out) to return descriptors for available devices. It doesn't actually attempt to access the instruments, and that would explain why you are able to find the instruments. I am not completely sure why you don't get any errors when you do a viIn16 and viOut16. If you try a command like viMove, do you get an error?

Thanks,

[Believer]

Hello _Belle,

You had said "When you call viFindRsrc, it simply looks at the Resman output table(C:\nivxi\tbl\resman.out) to return descriptors for available devices. It doesn't actually attempt to access the instruments,"

Are you sure? Why would you need a DefaultRM parameter in the function call? And more importantly what would happen for a GPIB slot 0 for which there is no resource manager to run, and consequently no resman.out file?

Thanks,

Ronnie

[Believer]

_Belle,

I searched my whole PC and could not find resman.out.

Are you sure about your previous post?

Thanks,.

Ronnie

[Ebele_Obijiofor]

Hi Ronnie,

I apologize for the confusion in my previous post. With the newer versions of the NI-VXI driver, the resman.out file is not generated automatically anymore. You can generate it by executing resman -o -l from Start >> Run.

I tried a few things:

• I Installed some VXI modules, powered up, ran resman, and did a viFindRsrc. Everything checked out fine.
  
• Next, I powered down, and removed one of the modules, and powered back up. In Measurement and Automation Explorer( MAX), I still had my old configuration with both modules, and when I did a viFindRsrc, it didn't return any VXI modules.
  
• I ran resman, and that fixed the entry in MAX to show only the VXI module I had installed, and viFindRsrc also returned the correct information.

So, what I would suggest is to run resman before you run viFindRsrc, and that will ensure that you get the correct information.

Thanks!
Regards,