generate signal rs 232

[fredazerty]

Hello,

I'd like to know how generate a square signal on the serial port of my PC. This signal will be use for starting video cameras by trigger.
Thanks for your response

[Henrik_Volkers]

you can control the DTR and RTS line (yes, and the Tx too but I wouldn't use that line)

open the port (VISA open or Ini serial port)

use the visa property node to control the serial lines (drop the bytes at serial port and select serial line settings )

(for Tx it's the break property, however .... )

[fredazerty]

Thank you,

I need to generate a 4 volts step. do you know how to configure visa for it?

Greetings from France

[Dennis_Knutson]

Out of the serial port? Can't be done without some external voltage shifting. The RS-232 transmit spec defines the output voltages as +5..+15/-5..-15. The parallel port comes a lot closer with it's TTL output.

[smercurio_fc]

If you search the examples that come with LabVIEW (Help->Find Examples...) you will find a VI called "Troubleshooting Serial Line Monitor" that shows you how to control the DTS and RTS lines. It's in the examples\instr\smplserl.llb library.