RS232 to mono plug interface

A mono plug eh?

Then its a one way communication with possible bits lost... But Hey Ho...

All you need is either the transmit or receive wire connected to your device (depending on whether its transmitting or receiving only) and a ground wire....

On a 25 way standard D' type RS232 plug / socket the transmit or receive is pin 2 or 3, you will need to connect the DTR (data terminal Ready) to either 0 pin 7? or to high such as .... I've forgotten...

But the good thing about RS232 is that you can play around until it works, no damage done... just try it!!!

John.

The OP did indicate a 9-pin D connector, where pins 2 & 3 are still transmit & receive, but data ground is pin 5.

I can't help but wonder if he is trying to connect RS232 to an audio plug, which clearly won't work, unless I'm greatly mistaken. Now it would be possible to connect the RS-232 signal to a tone generator, and have software interpret the presence of a tone as a one and the absence of a tone as a zero, or to a dual tone generator, and have software interpret the two tones as ones and zeros...

Hmmm... I just had a thought, based on your thought. "or to a dual tone generator, and have software interpret the two tones as ones and zeros..." Suppose you played those tones through a phone! You could send a message from one computer to another! NAH -- it would never work.

Yes it would! About 15 years ago, I did the electronics for a robotic machine that applies droplets of tissue culture onto trays of microscope slides for immunology testing. The controller was (and still is) a Macintosh SE computer. The X-Y motion is provided by a modified plotter, which uses the RS232 port. I still needed to control the Z (only up or down, no speed or other control, and no feedback) and to turn the feed pump on and off. I built a small circuit with two op-amp tone detectors, which 'listen' to the audio out port and control those functions. Last I heard (a few weeks ago) it is still running on a daily basis, using the original computer with no modifications. I've kept a couple of spare SEs in my garage for at least 10 years, as replacements, but never needed them.

It would be perfectly possible to send those sounds over a phone line. It would hardly be high speed, but fine for this kind of application. Remember the acoustic modems where you placed the telephone receiver in a pair of rubber cups? The one I used had a speed of 110 Baud, connecting a terminal in northern Ca with a computer in San Diego about 1975.

Dick

Actually I remember those old modems well. I was being tongue-in-cheek, describing a modem. Sorry.

Odd -- I replied to this earlier... but poof!

In any case, I agree with Electroman. You'd want to consider the tip of your plug to be the transmit signal, and the outer connector to be the signal ground.

You can read up on null modem cables (which is more-or-less what you would be building)here

Ahhhhh hi Ken, you have had posts go missing as well?

I'm sure over the last day or two I've lost a few posts and certainly I've posted and then gone back and thought where has the post I referred to gone?

John ?

Strange, isn't it? I think you are pretty close to my age, where we start to wonder if we are just having "senior moments".

Me too! Maybe it just happens to old folks.

I've started keeping a copy of the text until I verify that it is up.

Thank heavens it's not only me. I have had posts go missing and I thought that I was just imagining that I had posted something, I thought I was going even loopier that I already am.

I recently received a mail notification that somebody had replied to one of my posts. However when I followed the link there had been no activity on the thread for several days and no comment by that person in the thread at all.

Oooo.. me too. Are we all senile?

Nawwwww, if we are the majority, and it looks like it, then we MUST be right, or normal, and its the rest of the world which isn't in phase with us!!!

John.