RS232C - Serial
RS232C - Serial
(OP)
Hi guys
I've just been employed at a company that deals with monitoring systems. I sorta qualified in 1999, but because of a lack of experience I was unable to find employment in my field of study viz. Electronic Engineering. As a result of not working in my field over the last couple of years I seem to have forgotten most of my theory.
Please can somebody give me a brief run down of a RS232C or point me in the direction of a relevant.
- What is a RS232C?
- How does it work?
- What are its applications?
- What does it look like?
Guys, I need this info. ASAP.
Thanks
LearnerGP
I've just been employed at a company that deals with monitoring systems. I sorta qualified in 1999, but because of a lack of experience I was unable to find employment in my field of study viz. Electronic Engineering. As a result of not working in my field over the last couple of years I seem to have forgotten most of my theory.
Please can somebody give me a brief run down of a RS232C or point me in the direction of a relevant.
- What is a RS232C?
- How does it work?
- What are its applications?
- What does it look like?
Guys, I need this info. ASAP.
Thanks
LearnerGP





RE: RS232C - Serial
You can Google all this info of course, but I'll give you a quick summary:
1) RS232C is an interface signalling standard for serial line data transmission. It refers to the voltage levels, NOT to any particular word length, message protocol or other data information standards.
2) It's used for connections between computers and external modems, or any other pair of devices that need to communicate at moderate speeds, but only over relatively short distances. Usually there are separate lines for send and receive so that device can talk in both direction simultaneously ("full duplex") if they want.
If you don't understand serial data transmission then you will have to Google more for yourself.
3) RS232 uses an unbalanced (data + return wire)circuit and signals over this using bi-polar voltages, i.e. a logic 1 is +V and a logic 0 is -V. At any moment the line will be one or the other voltage: Zero volts is not allowed.
The minimum signal levels a receiver input must accept is +3V and -3V respectively. (I forget the exact spec maximum voltage range (plus/minus 25V?) but it can often be +12v and -12v from an unloaded driver device)
4) It does not "look like" anything! There are certain standards that have grown up from the computer/modem industry for use of standard D-Type connectors, either 9-pin or 25-pin, and these usually have agreed pin numbers for the various RS232 lines.
RE: RS232C - Serial
But, as said before. Google and learn.
Gunnar Englund
www.gke.org
RE: RS232C - Serial
That particular character has a lot of 'edges', so you can easily see and identify the bits on the transmit wire with a scope.
The reason it's defined down to very low data rates is that the very first transmitters and receivers (in teletypes) were mechanical devices, that rotated in unison even if miles apart, and tripped mechanical latches in particular angular positions if the wire was in a logic 1 state, and the combination of latches selected determined which character was impressed on the paper when the hammer came down. The start and stop bits were actually required so that the motors had time to accelerate and decelerate.
Last time I checked, the current standard was EIA-232D, but you can get enough information from Google that you don't have to buy it.
Mike Halloran
Pembroke Pines, FL, USA
RE: RS232C - Serial
RE: RS232C - Serial