How to Control 1 bit on a RS232 port?

[shunshin]

Using VISA can read or write data from RS232 port，if I want to control 1 line on RS232 High or Low? Does any VI can do this? Thank you so much.

Message Edited by shunshin on 03-22-2007 12:23 PM

[Dennis_Knutson]

Which line do you want to control? If it's one of the control lines like DTR or RTS, then yes. You use a VISA property node. Select Properties>Serial Settings>Modem Line Settings.

Message Edited by Dennis Knutson on 03-22-2007 11:31 AM

[ChillyWilly]

There is a Vi in the examples that let you turn on and off bits in the parallel port (LPT1), search for parallel in the examples and open the "Parallel Port Read and Write Loop.vi" 

I'm not sure if there is something similar with Comm ports (RSR 232 ports) but if you need digital lines and don't have the hardware the parallel port is the way to go.

[johnsold]

An RS232 port is a serial port so it only has one bit of data at any instant of time. And the data bit only stays on or off for aduration specified by the baud rate. It is possible to control the handshaking lines by using a property node.

Lynn