Tektronix TDS1002 rise time measurment problem

[jimbawb]

Thanks. Do you mean the original projecty driver on NI's website for Labview 8.0, unmodified? Because that is what i started off with and I was getting lots of framing errors and other strange things. Its interesting to note that it isnt just me having the problem though, I wonder what it is thats causing it. Maybe I should fire off a direct report to NI? Or do they monitor these forums a lot, im not familiar with the system.

I do not have access to GPIB unfortunately, I am having to use serial for this project. Thanks though!

[thehobbs]

You can identify NI participants in the forum by the blue blocks under their user name (yellow for non-NI).  I had the same framing issues with both drivers with these Tek scopes.  After 5 minutes of running an example from the project-style driver with serial errors, it just started working. I know this isn't very helpful, but I think it points to intermittent errors with the serial interface on the scope.  Once I established successful communication, it remained good after that.

You can try lowering the buad rates on the instrument and in the driver. You can also try different handshaking modes that the instrument supports.

[Albert.Geven]

Hi Jason

Can you forward this question to Tektronix. It seems that their quality is less than it used to be.

[thehobbs]

Good idea. I will report the issue to Tektronix...

Message Edited by Jason Hobbs on 01-30-2007 10:05 AM

[Scott J]

I seem to be having a similar problem with the Acquire Waveform.vi example in the Tektronix TDS 200 1000 2000 series library using Labview 8.2.  When I run this example, it seems to timeout and I receive the error:

Error-1073807346 occured at VISA Write in

Tektronix TDS 200 1000 2000 Series.lvlib:Error

Query.vi->Tektronix 200 1000 2000

Series.lvlib:Autosetup.vi->Tektronix TDS 200

1000 2000 Series Acquire Waveform.vi 

Possible reason(s):

VISA: (HEX 0xBFFF000E) The given session or object reference is invalid.

However, I have been able to establish basic communications with the scope and receive "TEKTRONIX, TDS 2014, 0, CF:91.CT TDS2MEM:FV:v6.08" back when I send "*IDN?\r\n" using the Basic Serial Write and Read.vi

I was working with an applications engineer earlier and he made sure I had version 4.0 of NI-VISA.

Any reasons why I seem to be getting a VISA error when communications should be ok?

Message Edited by Scott J on 02-06-2007 12:46 PM

[Albert.Geven]

Hi Scott are you sure that you filled in the correct visa resource name?
Or forgot somewhere to wire the resource name?

Is this the example shipped with the driver or is it modified?

only a few questions because you don't have a timeout but a wrong connection.

[Scott J]

Thanks for your response.

I am using the example shipped with the driver, so I can check that the visa resource name is wired correctly, but since it is unmodified it seems it should be correct.

Also, I believe the VISA resource name was correctly selected as com 7.  To test this I used the Basic Serial Write and Read.vi which returned a header.  All settings were the same in the  Acquire Waveform.vi example as in the Basic Serial Write and Read.vi.

[thehobbs]

This is a bit odd because I'm only familiar with that error when speicifying an incorrect resource name.  It seems that you are doing this because the Initialize VI and VISA Write in the Autosetup VI are executing without error.  Can you try using a built-in COM port (like COM1)?  Another think you might want to do is single step through the code or use execution highlighting to slow things down and see if that makes any difference (for the purposes of identifying the root of the issue).  You can also caputure the VISA calls by taking an NI Spy log.  That log may be of interest if you want to attach it here.

The example you ran should function properly.  I'm curious to know the results if you try a different example (that does not call Autosetup) or try simply running the Fetch VI.

[Scott J]

I single stepped through the code and discovered that the error was caused because I didn't receive a DCL after the VISA clear in initialize.vi.  I removed the VISA read in the begining of the case statement and this fixed the problem.  I assume the DCL wasn't being received because I have a serial to USB converter, but I'm not sure. 

However, I now have a different problem, and it's kinda tricky because the problem only happens when I step over initialize.vi, but not when I step through it.  The error is code 85 which says

Error 85 occurred at Scan From String (arg) in Tektronic TDS 200 1000 2000 Series.lvlib:Error Query.vi->Tektronix TDS 200 1000 2000 Series.lvlib:Reset.vi->Tektronix TDS 200 1000 2000 Series.lvlib:Initialize.vi->Scotts Series Acquire Waveform.vi

Possible reason(s):

Labview:Scan failed.  The input string does not contain data in the expected format.

I don't have to step any lower than Initialize.vi.  I can step over both Reset.vi and Error Querry.vi without trouble, but if I try to step over Initialize.vi, the error appears.  It is interesting because I would not expect format to change whether stepping through or running.  Any ideas?

[Scott J]

I put a 50ms delay inbetween two of the VISA commands and now things work well.  Think I'm on my way now.