How to modify a RS232 sniffer so that it does not load the communication link?

[ivar]

RS232 buffer

I wanted to sniff communication between two RS232 devices. Thishttps://embeddedfreak.wordpress.com/2008/08/17/rs232-serial-sniffermonitoring-circuit/ link presents a simple solution but I want to make sure that my 'sniffer' does not load the communication link.

To that effect, I was wondering if I could use a MAX-232 as a 'looping' buffer:
RS232 in -->TTL out-->TTLl in-->Rs232 out

The MAX-232 will be powered by an external 5v. Is this a fool proof way of sniffing without loading the line? Does the MAX232 even act as a buffer in this configuration? If not. are there inexpensive RS232 buffer ICs available? All the 74xx range of buffer ICs seem to work only at TTL levels.

 

[FvM]

Re: RS232 buffer

I had never problems operating RS232 with a fanout of two, connecting a second MAX232 or similar
receiver to an operating RS232 link to acquire the data through a simple Y-cable. I don't love to
make a simple thing complicated by adding superfluous hardware.