Re : Informations transmitted via USB

[rrado]

Hello,

I'm using a Tektronix scope. And under Windows, I control this instrument through the NI-Visa library.
But the scope hangs, in some cases, which happen quite often : in these cases, we always get a "timeout" answer, no matter which request we send to the scope.

I contacted Tektronix support, and they told me :
"I have duplicated this condition and found the only way to break the
cycle was to do a visa clear, close and then reopen the visa session."

Could you tell me which informations are transmitted to the scope during these commands?


Thanks,
R. Rado

[ManuelR]

Hello,
is it a serial or a GPIB communication?
Is it a timeout response from tektronix instrument or the VISA function return a timeout?
I beleive that the instrument lose the communication so you need to start another one. Did you try to only close the communication and try to start it again without using the VISA clear function?
The VISA clear function is doing a Selected Device Clear.
Regards,

Message Edité par ManuelR le 10-09-2007 07:40 AM

[rrado]

. is it a serial or a GPIB communication?
I'm using a USB connection to communicate with the device.

. Is it a timeout response from tektronix instrument or the VISA function return a timeout?
Tektronix instrument completely hangs, and doesn't answer anything any more.
So, the VISA function (and any other way to communicate with the instrument) times out.

. I beleive that the instrument lose the communication so you need to start another one.
. Did you try to only close the communication and try to start it again without using the VISA clear function?
. The VISA clear function is doing a Selected Device Clear.
The thing is that the only way to unblock the device was to completely close the VISA program (OpenChoice Talker Listener, for instance), and open it again.
Under Linux, I tried to execute visa clear + close + open, but it didn't unblock the device.

The only way to unblock it was to
- Use windows,
- Open "OpenChoice Talker Listener"
- Send a request (*idn?, for instance)
And then, the device was unblocked.


That is the main reason why I'm requesting your help to get the USB informations which are transmitted to the instrument, when using VISA (under Windows?).


Regards,
R. Rado

Message Edité par rrado le 10-09-2007 03:24 PM

[ManuelR]

Message Edité par ManuelR le 10-09-2007 08:22 AM

[ManuelR]

Hello,
what do you mean  by "OpenChoice Talker Listener" ?

[rrado]

"OpenChoice Talker Listener" is a software provided by Tektronix, and using VISA library.

[ManuelR]

Hello,
Do you manage to correctly communication with the instrument using Linux? This is strange that the same fonctionnality do not unblock your instrument. Is it NI instrument driver? Do you know which function make the instrument hanging?

[rrado]

Here is the way I get the scope hanged:

1. (send) *IDN?
2. (read) TEKTRONIX,TDS 2004B,C010XXX,CF:91.1CT FV:v22.01
At this point, there is no problem.

3. (send) *IDN?
4. (read) TEKTRONIX,TDS 2004B,C010XXX,CF:91.1CT FV:v22.01
5. (read) - timeout -
At this point, it is still a normal reaction : no request ==> no answer


6. (send) *IDN?
7. (read) - timeout -
8. (send) *IDN?
9. (read) - timeout -
From point 6, we've got a problem : no matter which request we send to the scope, it hangs.
And the only way to make it work again is to quit the program, start it again, and send a new query.