Why can't I communicate on rs232 using Win 7?

[mot4755]

The same VI works using XP.

I am able to use Hyperterminal in Win 7. It works fine.

I just can't seem to get Serial VISA functions to work.

I'm using Labview 8.5

I've attached the VI I'm using.

[Albert.Geven]

is your version of VISA supported by win7?

[mot4755]

Yes. NI-488.2

Says so right on the CD.

[nyc_(is_out_of_here)]

Since you are using Win7, the PC probably has faster CPU than the PC running XP.

You might want to try a delay after the write and before you query for the number of bytes on the port.

[Dennis_Knutson]

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@mot4755 wrote:

Yes. NI-488.2

Says so right on the CD.

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What the heck does NI-488.2 have to do with anything related to serial communication? You also should know that LabVIEW 8.5 is not officially supported on windows 7. You should also know to connect an error out indicator to see what (if any) error you might be getting.

[mot4755]

Because I'm using the VISA Serial Pallet ??

Anyway, I tried delays, slow execution, breakpoints. I'm getting no data after the write.

No errors either.

Oh, and I tried VISA 5.0.3 too. No help.

[mot4755]

I meant I was using VISA 4.4.1 version

488 was a typo

[crossrulz]

Do you have access to an oscilloscope to make sure data in going in and out of the serial port?  Where did you add delay?  You should put in a delay after writing the data and before reading (bytes at port node).

[Dennis_Knutson]

I'm glad you are now talking about the NI-VISA driver instead of the NI-488.2 driver.

So, is it returning 0 bytes? Your VI is not the best written for serial communication and a termination character. You are configuring the VISA Read to terminate on a LF character but you are sending a CR. When you have an instrument the uses a termination character, the VISA Read has to be configured the same way as what you are using for the write. You also do not use the VISA Bytes at Serial Port when the instrument uses a termination character.

[mot4755]

I was able to use the older serial functions to make it work.

Doesn't maks sense, but it works.

See screen shot.