RS232 replecement with NOT gates

Hello,

Perhaps a problem with signal levels. RS232 needs a voltage of something around 10 volts for Low and -10 volts for high state on the RxD and TxD lines. I think your inverter puts only 0 volts and 5 volts onto the lines. Sometimes this would work, but the 0 volt level might be the problem for the receiver in your computer.

Try to use a different RS232 transceiver, for example MAX232.

Jochen

"I didn't use rs 232, but I replacement with NOT gates. sometimes run and sometimes not run, I don't know why????"

What else do you expect?!

The computer has an RS-232 port - it is designed to work according to the RS-232 spec. If you connect it to something that is not RS-232, why should it work? It will only ever work by luck.

"Try to use a different RS232 transceiver"

His problem is precisely that he has not used any RS232 transceiver!

i think he dont use MAX232 or IC RS-232 converter. Like this
http://microengineeringlabs.com/resources/pbpmanual/5_61-5_64.htm

"i think he dont use MAX232 or IC RS-232 converter."

There's no "think" about it: he specifically stated that he didn't - and the results are just what is to be expected!
He is reaping the benefits of his folly.

Note that the web page you cited says,

"... allow most applications to run without level converters" (my emphasis).

If you want something that you know will work, rather than just hoping that "most" of the time is good enough, you must use a proper RS232 transceiver.

As that page also says,

"... single-chip RS-232 level converters are common and inexpensive ..."

once more:
The question: "I am not doing it right, why does it not work" does not make any sense.

Erik

Whenever I use the bathroom, I make a terrible mess. I am not opening the toilet lid, instead am just leaving it down.

What's wrong? Why does it always make mess?