Can't communicate with Agilent 34401A Multimeters anymore

[carolyne]

Hi everybody,

I'm working with Labview 8 and Windows 2000 (XP as well) and I don't understand why suddenly I can't acquire data from my Agilent 34401A Multimeters because I've worked with them since the beginning of my project and I haven't had any issues before so I send to you the error message and I hope you will set me straight about that:

Error -1073807339 occurred at VISA Write in Agilent 34401.lvlib:Control Mode.vi->Agilent 34401.lvlib:Initialize.vi->Agilent 34401 Read Multiple Measurements.vi

The difference between before and now it's that I've added some other devices in my assembly but all of them are working ok (I've added a COM HUB and a Analog Voltage Output device (USB 3112 from Measurement Computing Company)).

Do you think it can be linked with this ?

I think I have a problem with the Agilent low level VIs but I don't want to touch anything i'm not up to do that.

If anyone can help me...

Thanks

[Will.D]

Your error code corresponds to "Timout expired before operation completed".

Are you trying to write/read multiple things at the same time?  If so, are you doing so in order - i.e. read A, read B, read C, write A, write B...etc?

Are you not specifiying a timout/are you able to with the low level Agilent VIs?

If I remember correctly, if you try to read the Agilent meter after is has already been read you will get a timout error since it flushes the output buffer once it has been read.

[carolyne]

Dear Novatron,

Even with using the Read Mutilple measurement.vi you give with drivers it doesn't work and I think examples do the good process with reading and writing.

For the moment I've diconnected all other devices to just run one Agilent Multimeter with a simple example of Labview and it's the same...

Have you got an idea ?

[Will.D]

Have you tried going to MAX to try to communicate with the instrument?

Are you communicating with GPIB, Serial...?

I generally do not use the drivers that companies provide with their products, as I've found too many that are very poor.  If you take a small bit of time, you might find it very useful to learn how to communicate with your instrument with just the Serial/GPIB (or whatever you're using to communicate) VIs.

The time taken to learn this method would pay off if you're planning on a lot of instrument control in the future.

However, if you would prefer not to go that route, post your VI with just the Agilent meter communication (save as development distribution), and someone will figure it out!  ...at least those with access to an Agilent 34401.

[Dennis_Knutson]

Go to MAX and verify that the instrument can still be detected. Then, try to communicate with the instrument. If you are able to to do a *IDN? query and get results back, then you have no basic problems with the instrument or the GPIB bus. If you continue to have problems when taking a measurement, then maybe something has changed in your code or setup. For example, if you are using a trigger to generate a measurement, if the trigger is not generated, you have no measurement to read and you will probably get a timeout error.

[carolyne]

Hi Dennis,

I can communicate with the multimeter and get an IDN so it's ok and I've looked at the code and the trigger is settled "immediate", the timeout is 10000ms. They are default values and it worked very well like this before.

To answer the Novatron question, I'm using a RS232 port.

I don't know why the error message told me there is a problem in the VISA Write vi in the control mode vi. I'm sure it's just a code problem.

I send to you the VI if you want to check everything is right...

[carolyne]

Ha !

It's ok I've found checking with the same example on another PC that the configuration of the flow control and the stop bits were changed so I've tried with the good settings and everything is ok now !

Now I will find the one who changed that and he will heard about me !!!.... 😉

[Dennis_Knutson]

I don't have 8.0. Can you save it to 7.1?

[carolyne]

Hey guys,

I have always the same problem today and I don't know why and what is the reason.

I've checked what I told you yesterday and it's ok but even it fails...

Can you tell me how to do to save the VI in the 7.1 version to send it to you ?

Thanks

[Dennis_Knutson]

I don't know if I want to now after getting only 2 stars.

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