RS232 connection with 3-wire setup

[MVTStudent]

I'm trying to connect a scale to the serial com port of my laptop. Does anyone know, if the Labview function "Instrument Assistant I/O" needs the CTS and DTR pin?

Or is it possible to connect RxD, TxD and Ground? My scale only needs a send command (P) on the RxD pin to send the current value.

My first try failed and I couldn't get a working connection.

Thank you for your help!

[crossrulz · Accepted solution]

I wouldn't worry about using the Instrument Assistant.  Instead, use the actual VISA API.  It will help you in the long run.

To start, use the VISA Configure Serial Port to set up the port.  Typically, the only thing you will need to adjust is the Baud Rate.  But it really depends on the instrument.  After that, then VISA Write to send the commands and VISA Read to read data back.  When everything is done, use VISA Close to release the resource.

If you want more help, then you will need to give us more information, such as the manual for the scale so we can dig into the commands and serial settings.

[MVTStudent]

Thank you for your help! My connection is now running.

Just a little note for anyone reading this. I also made the mistake, that I didn't check the automatic port closing function of Labview.

It can be found under Tools -> Options -> Environment and checking "Automatically close VISA sessions."

[AeroSoul]

Or use VISA Close function.