Error -1073807343: Resource not present?

[blockheadjr]

This is an offshoot of this thread:

http://forums.ni.com/ni/board/message?board.id=170&message.id=145602

Since that issue was cleared up, I've run across a new error claiming my AC Load is not present.  Again, this exact same Labview program worked fine before, so my first instinct is that there is still something that needs to be loaded that is missing.

Some background:

- I am using a new PC, and this is my first attempt at running a Labview VI on it.
- This same VI functioned without incident on my previous PC (which died).
- I'm using Labview Express 7.1.
- I'm using a GPIB inteface.

What I've tried so far to solve the problem (all of which have failed):
- Uninstalled and reinstalled Labview.
- Downloaded and installed NI-VISA 3.3.1 driver (latest version).
- Confirmed that MAX 'sees' all the correct instruments on the GPIB connection (Labview engages remote control of my instruments, and responds to *IDN? queries, so I'm guessing that comm isn't an issue).
- Confirmed I have the latest IVI Compliance Package loaded.
- Confirmed that the function name and parameters in the Library Call Node are correct (they worked before), and that the calling convention is correct.
- Built a new VI from scratch that just employs the Library Call Node (and required inputs and outputs).
- Alternately sweet talked/cursed at the monitor.

Here is an NISpy capture of the problem:




Any suggestions?

[Robert M]

Hi blockheadjr,

Under what name does your device show up in MAX? 
What name or address are you using in your LabVIEW program?
What IVI driver are you using?

[blockheadjr]

Here are a couple captures for your perusal.  The instrument VI worked fine before, and it hasn't been changed.

Note in the cicld30 Initialize.vi Front Panel, the GPIB instrument address is GPIB (Address 2): "GPIB::2::INSTR", and that MAX defines instrument 1, addres 3 as the AC Load in question.  Am I to understand that the GPIB addresses were automatically changed between the last computer and the latest?

[Robert M]

Hi blockheadjr,

How the addresses changes really depends on the instruments.  Are their addresses set by dip switches or can they be programmatically changed?  However it was done, you need to match up your LabVIEW application with what you are seeing in MAX.  Changing "GPIB::2::INSTR" to "GPIB::3::INSTR" should do the trick.  To look at and configure what these low level settings and names are, you can use the VISA Interactive Control (VISAIC).  Please let me know if changing the address works for you.

Regards,

[blockheadjr]

Thanks, Richard.

I attempted to change the GPIB address in the Initialize.vi, but found that in running the VI the address field would automatically switch to "AC Load".  This is not an option on the drop-down menu for that VI.  I figured it had to do with the resouce input, so I disconnected that and reran, with the same results. 

I might also add that my forehead has become noticibly flatter from beating it against my desk so much.  It may be time to pull in an expert.

Bryan_____

[blockheadjr]

(BTW - I did use MAX and VISAIC and confirmed the correct GPIB address, and that I could in fact communicate with the AC Load.)

[Dennis_Knutson]

In MAX, do you actually have the VISA alias ACLoad created?

[blockheadjr]

No.  The only place where "AC Load" appears (that I can find) is in the I/O Name Control box shown in the Initialize.vi Front Panel.

[Dennis_Knutson]

Okay. In MAX, you can define an alias for any instrument. With an alias, you don't really care what the actual address is. This is handy when a piece of code might be used on different testers and the address for instrument a on tester 1 might be one thing, and the address for instrument a on tester 2 might be completely different. An alias is also useful as a descriptive VISA Resource Name. In your case, the resource name of ACLoad would mean more than GPIB0::2. So, open MAX and select the instrument. Right click and select Rename.

[blockheadjr]

You nailed it, Dennis.

I opened the VISa properties tab, and the naming field was blank.  Filled it with "ACLoad", reran the program and the error was history.

Good eye.  Thanks for bailing me out.

Bryan______