How long distance for RS232 ?

[iugmoh]

Hi all
I use MAX232 or DS275 with PIC16f877A to make serial communication, anyone know how long distance for this communication ??

[mat janssen]

For rs 232c communication is 1200 m max.
If you change it to rs422 or rs485 then a few Km more is no problem.

[mackrackit]

For rs 232c communication is 1200 m max.

In real life with RS232 you can expect around 100 feet (30 meters).
I am talking a reliable setup with good shielded cable and the environment used in does not have great amount of noise (electrical).

[Charles Linquis]

It depends a lot on the cable and the baud rate. Many years ago, I ran 115Kbaud through 100' and 19.2Kbaud through 300' of expensive shielded cable. It was for PC network that ran through serial ports instead of Ethernet.

[iugmoh]

Thanks for your replies

I think that RS485 will be a good choice for long distance as I read in some sites

[Ioannis]

What is your definition for long?

Ioannis

[sayzer]

A little experiment from real life:
I am already using 50m cable from one 16F628A to the other with perfect result.
There is nothing in between. Just two PICs with HSerOut and HSerIn commands.

[Ioannis]

It is possible depending on speed, cable, interference and drive and input electronics to obtain more range than what the standard supports. But to be on the safe side, choose the right tool for the job to have repeatable results.

So, even if the 50m that Sayzer succeeded in are impressive it could be even longer for a more powerfull drive circuit and a more sophisticated input front-end. But for what reason when you have at hand the most reliable and cheap RS-485 chip, SN75176 and of course all other clones that work similar, better or faster? It is made for the long range network and it does that in an easy and perfect manner.

Used it alot and had no problem either in short or long distances. In fact I like it so that even for very short distances I am considering to use it because of the multi drop features.

Ioannis