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Measurement and Automation Explorer: GPIB communication tool is freezing Tektronix scope



wha@atmel wrote:
Hi Jen,

First: What kind of TEK - scope do you use ?

Why do you want to invent the wheel again ??? - especially if yours has four corners ??

@try to use / modify the drivers delivered by TEKTRONIX - search for your scope @: http://zone.ni.com/idnet97.nsf/browse/

Find attached a sub.vi for channel reading (TDS 7054) - there you have to specify the lenght
"entire waveform" etc.

Hope this helps to guide you into the right direction.............

Regards
Werner




I took a look at your code after I downloaded the Tektronix drivers.. Maybe I'm not understanding. Are you talking about the LabView wrappers Tektronix puts out?

I don't see where you're using the Tektronix VIs in your program. It looks to me like you are doing VISA read/write; that's essentially the same thing I have in my program, except mine is a loooooot more simple. (As I said, basically it's read curve, read curve..)

And my program was working before. I just didn't know how many bytes to put in the "byte count" in the VISA Read. That yields a warning, not an error.

The problem I'm having is not with LabView but with NI MAX. MAX uses the same VISA communications tool, right?

jen
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Hi Jen:

When using a VISA session in MAX, in the Read tab, have you tried specifying 8008 or even 8010 as the count? Do you still get the same problem?

In response to a previous question, clicking the 'X' to exit from the VISA Interactive Control, does close the VISA session.

Please try these byte counts in MAX.

Regards,

Emilie S.
Applications Engineer
National Instruments
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@Emilie S. wrote:
Hi Jen:

When using a VISA session in MAX, in the Read tab, have you tried specifying 8008 or even 8010 as the count? Do you still get the same problem?

In response to a previous question, clicking the 'X' to exit from the VISA Interactive Control, does close the VISA session.

Please try these byte counts in MAX.

Regards,

Emilie S.
Applications Engineer
National Instruments




I just tried increasing the byte count to 8010.

This time the Tektronix did not crash. 😄

It read 4007 btyes (I turned the resolution down to two bytes per point also).

Is the general method of the VISA read/write to overestimate the number of bytes and then try read it?

Thanks!
🙂 jen
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Message 13 of 14
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Hi Jen:

Generally speaking, yes, over estimating the number of bytes is better than under estimating especially in this case. If you don't specify enough bytes then there will be data left in the buffer and that, as you have seen, can cause problems. The only problems I have seen with over estimating is that if you, for example, write a command that returns 100 bytes, then try to read 200 bytes twice in a row, you will get a timeout error in the second read.

Sounds like this is working for you now though, so I would just go with it.

Have a great day,

Emilie S.
Applications Engineer
National Instruments
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