RE: RS232

["Dave McLaughlin" <dave_mclaughlin@xxxxxxxxxxxxx>]

Having interfaced to so many RS232 devices over the years I wonder if
you
might find the following information helpful in determining which pin is
which.

Normally the device has either a 9 way or a 25 way. If you don't have any
wiring information, it is quite easy to find which pin is TX and which is
RX. This is assuming they are on pins 2 & 3 as normal which it most
likely
is if using the standard D type connector.

Using a multimeter, check for a voltage between pins 2 and ground (pin 5 on
the 9 way and pin 7 on the 25 way) and pins 3 and ground.

If you find anything from -3V to -12V then this the transmit pin. The
receive pin will have virtually no reading on it. By the way, do this with
the connecting cable disconnected. If this device is transmitting you might
see a small change in the voltage and it will go positive if there is a
long
transmission but this depends on how good your meter is.

Now repeat this on the other device and now you know which pins to connect
together.

If you need handshaking, you can repeat this process but generally RTS and
CTS will always be the same for all connectors, it has generally been found
from my own experience that the TX and RX pins are the 2 that catch you out
and my quick and dirty meter check has saved me a lot of head scratching in
the past.

Dave.


> ----- Original Message -----
> From: Rob Mouser
> To: ukha_d@xxxxxxx <mailto:ukha_d%40yahoogroups.com>
> Sent: 25 January 2009 20:53
> Subject: [ukha_d] RS232
>
>
> Hi All
>
> I'm getting all confused with RS232 on my Arcam AVR350 Amp. I'm
> trying
> to send RS232 commands to it from my Pronto 9600 serial extender.
The
> extender software gives me two choice "ASCII" or
"HEX". Page 38 of
> the
> manual details the RS232 settings but I'll be buggered if I can get
> them
> to work but to be honest I'm not completely sure I understand the
> document! http://www.arcam.co.uk/downloads/DiVA%20AVR350%20E.pdf
>
> If any kind sole fancies taking a look at the manual and telling me
> what
> strings and format I should be using for (say Zone 1 On and Off) I
> would
> be very grateful.
>
> I was going to try and test sending commands to the Amp via
> HyperTerminal (if that program still exists) but soon realised that
I
> no
> longer have a PC with a serial port and can't find my USB to Serial
> dongle anywhere!
>
> Isn't it amazing how you can waste a Sunday afternoon!
>
> TTFN
>
> Rob





[Non-text portions of this message have been removed]


------------------------------------