How to read waveform from TDS 201

[Yan_18]

Hello,

I've used Labview previously but my labview coding skill is limited.  What I am trying to do is extract data from a TDS201 through RS232 serial port.  I am using an adapter to connect from the RS232 to an USB port on my computer.  I'm trying to collect a screen capture from the oscilloscope using Labview.  There are several issues here. First, I used Measurement and Automation to see which port the Oscilloscope is using. However, it seems like the computer does not recongize it. It sees the USB-RS232 adapter but not the oscilloscope. When I used my previous program that I inherited for TDS 450, I see no waveform on the screen.  Of course, I will need to change a few elements in the current code that I am using but I don't have the background for this.  If anyone could provide some suggestions, I would really appreciated.

Thanks!

[Dennis_Knutson]

MAX will not and it should not find an instrument connected at the end of a serial cable. That would be silly to try every possible combination of com settings, etc. to get a response.

Absence any details of this 'older' program, kind of hard to make any recomendations. If it was written with VISA functions, about all you would have to change is the addition of configuring the serial port and termination character. Look at how its down with the 34401 example that comes with LabVIEW.

[Yan_18]

Can you suggest another way to connect from the Oscilloscope to the computer? Unfortunately, I can not get access to GPIB cable in China.

Yes, I'm using VISA.  I'll take a look at that example and get back to you. Thanks!

[Dennis_Knutson]

Why do you need another way if you have a serial cable? Just because MAX does not attempt to find an instrument connected to a serial cable does not at all mean you cannot use it. Test the connection with Hyperterminal and if that works, you can do anything you want in LabVIEW.

[Yan_18]

I did test it with the hyperterminal. However, I had no luck.  There was nothing written on the screen when I asked for it to capture data.  Is there another way for the computer to see the device?

[Dennis_Knutson]

Start with something simple. Just send *IDN? perhaps. If that does not work, then check and make sure the com settings on the scope match the com settings on the pc. If that does not work, check the type of serial cable that you are using. There are two type - null modem and straight through. I suspect you would need a null modem type. Verify that it is or isn't. If the cable is correct, verify in the scope manual that the serial port can actually be used to control the scope and is not just for connecting something like a printer.

[Yan_18]

I apologize. I do not know what does *IDN means.  The setting does match for the com settings on the scope and the PC. The oscilloscope is connected to the computer through a null modem then to an RS232-USB adapter.  The manual just states hardcopy to printer. However, I saw an pdf online and someone has done it. http://www.ece.vt.edu/cel/help/TDS-210-waveform-capture.pdf

How do I know tihs hardcopy button works? I pushed it and nothing happens. Is there a way to check?

[Dennis_Knutson]

If you do not know what *IDN? does, then I suggest you read the programming manual for the scope. I don't know for sure whether your scope supports that command but it's been a standard for GPIB instruments for over 20 years. It's a query to tell the instrument to return identification information.

In any case, apparently the scope does not support remote programming over the serial port. The pdf file supports that. It is just using Hyperterminal to capture the data that would normally be sent to the printer. You can capture the same thing with LabVIEW and manually press the button.

If you duplicate what the pdf describes and don't see anything in Hyperterminal, perhaps you should try a straight-through cable. What does the manual say about connecting to a printer?

[Yan_18]

I read the user manual for the oscilloscope but there's no mentioning of *IDN. I guess it does not support that command, although it is a GPIB instrument.

This is all the manual say about the printer. Push the HARDCOPY button to print a hard copy of the display. The hard-copy function requires that an extension module with a Centronics, RS-232, or GPIB port be installed and connected to a  printer.

That's about it. The manual isn't very help. The oscilloscope looks really really simple yet I can't find anything useful. =/

I'll try a straigh-through cable and see what happens. I'll have to wait until I return to the States. I couldn't find in China at least.

Thank you so much.