DC Bias on 4276a initiated by Labview

[Erny123]

I am working with the 4276A LCZ Meter, and I have downloaded and installed the driver for it. However, I open up the example VI and it seems to work except it puts out the error "ERROR 1300" in Labview and on the realy instrument it displays "ER 13".
I talked to my colleagues about this and it seems that there is some assumptions made by labview over the instrument. In the 4276a manual (Section III, 3-14) (page 56 in pdf), it says that this error occurs if internal DC bias voltage was set via the HP-IP but instrument is not equiped with Option 1 (Which is a DC Bias Supply), or it occurs if the comparator enable code (E1) was sent via the HP-IB, but the instrument is not equipped with option 2 (which is a comparator/handler interface).

Well, this 4276a is not equipped with either option. The switch on the instrument that turns on the DC Bias is off. However, as you can see from the picture showing my error, there is a DC bias in the VI itself.

So I am wondering, how would I go about turning off the DC bias or stopping LabView from turning it on? I have looked through the subVIs that make up this example.VI and there is no code that inputs the string "E1" for the enable code, so I don't believe the error occurs because of the Option 2.
I have added the block diagram for the example.VI. In addition, I added the subVi (ConfigTestSignal.VI) which contains the DC Bias input.

Let me know what you guys think. THANK YOU!

[Erny123]

I can't upload the manual because it gives me an error but here are pics of the error and DC bias options (which this 4276a has none of the options):
Edit: Just found something in the manual that says the DC bias switch is not HP-IB programmable: "The switch controls the internal DC bias source only....Also, this switch is not HP-IB programmable"

[0utlaw]

Hello Erny123, and welcome to the forums!

Remember that the example you're using is just that- it is unlikely to provide you with a perfect solution for your device/situation.  Also- this particular device driver appears to have been provided by the manufacturer, so it might be worth getting in touch with them to see if they have any additional examples that might be more relevant to your hardware/application.

If your hardware doesn't support biasing, then you'll need to remove or disable the portion of the code that attempts to configure the bias settings- this is the second "Format Value" block that is appending the BI<value> to your command string in HP4276A Config Test Signal.vi.  If you're having trouble finding this, use Ctrl+H or click the yellow question mark at the top-right corner of your window to bring up the context help. The format string being used for that particular function is %.;BI%.1fEN.

As for the bias switch and the description you quoted- my interpretation of the manual is that the switch itself cannot be toggled or overridden using GPIB commands.  The physical switch is the only way to enable biasing, but if enabled the bias itself can be configured remotely.

Regards,

[Erny123]

Thanks Tom. Do you know what the string "%.;BI%.1fEN" indicates? How would I go about changing it to turn off bias?
I am new to labview but I see now that it's better to begin a new program that will avoid the biasing. 

[0utlaw · Accepted solution]

Hello Erny123,

I've not read the manual, but I would guess that BI is a string that indicates a bias configuration, and EN indicates the end of the command.  "%.1f" is a format specifier that inserts a floating-point decimal value with one digit of precision (refer to that link for the syntax requirements when using the Format Value function). Just above that you can see that a similar format function is used to insert the test frequency into the command string using FR rather than BI, and a slightly different numeric format.

The example you're using hasn't been written using the standard LabVIEW style, so it may be a little hard to track what inputs and outputs go where.  Try clicking the Clean Up Diagram icon in the example's block diagram to re-order things in a more logical left-to-right fashion. 

What this VI is doing is composing a string of commands to send to the instrument- you'll need to refer to the manual to see what the format requirements are, but I would guess that you can just delete the second format value function and wire the output of the first through to the send message VI. 

I wouldn't say that you need to start from scratch every time, but yes, you'll need to make some modifications to this example to get it to work for you.  I'd strongly recommend that you go through one or more of the LabVIEW tutorials available online, it'll save you a lot of time in the long run.

If you have an active support contract and your software serial number has been activated on your ni.com account, you should have access to the LabVIEW Core training online here:

NI Online Self-paced-training

https://lumen.ni.com/nicif/us/LMS_LOGIN/content.xhtml?du=http%3A%2F%2Fsine.ni.com%3A80%2Fmyni%2Fself...

if you don't have access to that, there are a number of other intro to LabVIEW tutorials available on ni.com The links on the right-hand side of this page are a pretty good place to start for online tutorials:

Academic LabVIEW Training: How to Learn NI LabVIEW

http://www.ni.com/academic/labview_training/

Regards,

[Erny123]

Thank you for all your help!
I cannot seem to find anything in the 4276a manual about the string input for the bias but I will keep looking. I will also try deleting the second format value function. 
I have gone through a couple of tutorials already but I still very elementary in labview so I will continue doing more tutorials. 

Again thank you for all your help. 

[Erny123]

Thanks again!
Just deleted the second format value function and works perfectly now.