Author Topic: HELP MAX232  (Read 1700 times)

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Offline qwertyTopic starter

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« on: August 05, 2009, 03:09:04 PM »
Hello. I'm having a problem with my project, and I hope someone could help me.
I have 2 MAX232 interconected working well (TX1 to RX2 and TX2 to RX1) there aren't problems, the probles is I want to spy what signal is sended from TX1 to RX2 whith one third MAX232, like one MAX232 are sending simultaneously one signal to other two MAX232. Well this is my problem I hope someone of you can help me 'cause I've been serching information about this topic and I can't foud it. Thanks

Offline Soeren

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« Reply #1 on: August 05, 2009, 05:34:33 PM »

Your terminology is incorrect and that makes it difficult to explain this to you. There is no such pins like TX1, TX2, RX1 and RX2 oin a MAX232.
The correct pins are (pin numbers in square brackets):

Logic level

To make a two-way spy/sniffer, you need to use two receivers (one MAX232 contains them both). Pins 8 and 13 connects to a "RS232"-level line each (TXD and RXD) and the sniffer logic connects to pins 9 and 12.

If you just want to listen in on a single line, just connect eg. pin 8 (R2IN) of the extra MAX232 to the "RS232"-level line that you wanna monitor and connect your sniffer circuits logic level to pin 9 (R2OUT).

You should never connect two transmitters to one line of course. It won't hurt anything (provided the EIA/TIA232 protocol has been adhered to by the equipment manufacturers), but the data stream will be like psychotic babble.

If you've got an old PC with a serial port, you can just use that with a sniffer program and hook up the RXD of the serial port to the line you want to monitor.

What protocol are you trying to hack?
Did you search for somebody who allready did the work, to save a lot of time - most protocols are hacked within days afer their release.

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives


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