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Ori Idan
Posts: 12
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Reading CTS or DSR lines of Serial port

Is there a way to read the status of CTS or DSR lines of a serial port?
Also in what pins are these lines on standard PC?

--
Ori Idan
Helicon technologies LTD. National Instruments Alliance member in ISRAEL

Email: ori@helicontech.co.il
Home page: http://www.helicontech.co.il
Tel: +972-6-6262353 Fax: +972-6-6262405
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Member
Vlad Dragomir
Posts: 17
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Re: Reading CTS or DSR lines of Serial port

Hi!
You should try this using VISA function, which can be founded in Instrument
I/O->VISA pallete. If you open a VISA session foe a serial instrument, you
will be able to acces various parameters of the serial port, includind reading
the CTS and DSR state.

Regards,
Vlad Dragomir
Member
Steve Drake
Posts: 54
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Re: Reading CTS or DSR lines of Serial port

On Thu, 04 May 2000 16:47:40 +0300, Ori Idan wrote:

>Is there a way to read the status of CTS or DSR lines of a serial port?
>Also in what pins are these lines on standard PC?

25pin 9pin Signal Direction Description
1 - - - gnd
2 3 TD DTE>DCE tx data
3 2 RD DCE>DTE rx data
4 7 RTS DTE>DCE request to send
5 8 CTS DCE>DTE clear to send
6 6 DSR DCE>DTE data set ready
7 5 - - signal ground
8 1 DCD DCE>DTE data carrier detect
20 4 DTR DTE>DCE data terminal ready
22 9 RI DCE>DTE r
ing indicator
23 - DSRD DCE<>DTE data signal rate detector

Think of DTE as the computer.

I don't memorize this stuff it comes from a very usefull book called
"The Indispensable PC Hardware Book" by Hans-Peter Messmer.

While I've used the serial vi I didn't have to use the control lines
so I have no experiance there.

Hope this helps.

Regards,

Steve Drake
Member
Steve Drake
Posts: 54
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Re: Reading CTS or DSR lines of Serial port

On Thu, 04 May 2000 16:47:40 +0300, Ori Idan wrote:

>Is there a way to read the status of CTS or DSR lines of a serial port?
>Also in what pins are these lines on standard PC?

While looking for info on printing I found the following:

How can I control the DTR and RTS serial lines?

Serial Port Init.vi can be used to configure the serial port for
hardware handshaking; however, some applications may require manual
toggling of the DTR and RTS lines. Because the interface to the
serial ports is platform-dependent, each platform has a separate
mechanism to control the lines.

(Windows) The LavVIEW for Windows distribution contains a VI which you
can use to drive the DTR and RTS serial lines. The VI serial line
ctrl.vi, located in vi.lib\Instr\_sers
up.llb, can be used to control
these lines. The VI will toggle these lines according to the function
input. Valid codes for the input are:
0 noop
1 clear DTR
2 set DTR
3 clear RTS
4 set RTS
5 set DTR protocol
6 clr DTR protocol
7 noop2

(Macintosh) ..................

(Sun).............................

From LabVIEW User Manual page B-13

Hope this helps.

Regards,

Steve Drake