Chris Campbell wrote:
I need to be able to look at the bits/bytes going back and forth on a
serial line. I don't really need to *emulate* anything in particular,
like *be* the DTE or DCE, I just want to sniff the line that two other
devices are talking on so I can troubleshoot. Besides RS232, I need
it to do 422 and maybe 485 (e.g. address filtering). This is for
pretty low speeds -- 38400 max and I could even live with just 19200.

The PC-based tool I'm using now just suuuuuucks. At a previous job we
had a small standalone HP analyzer which was extremely useful;
naturally I don't remember the model name but googling around leads me
to think it was an HP 4951x. That model apparently has some storage
capabilities -- I don't need that either (just a RAM capture is fine).

Can anyone suggest similar analyzers for this purpose? No SONET, no
STP/UTP, just plain old low speed serial lines ... Once I have some
models identified then I'll start looking for used units.

Thanks!

Try the good ol' HP 4952A with the pod for RS-232 and RS-422. There are
many pods available (for ISDN too) but I don't remember anything about
RS-485.
Regards
Franco