5 Sep
2002
5 Sep
'02
10:23 a.m.
On Thu, 5 Sep 2002, Tony Duell wrote:
Maybe the confusion occurs because one of the most common RS-422 receivers is
the 26LS32C which does have a +- 15V input range (+- 25V abs max)
Eric Smith wrote:
I am _darn_ sure that the RS422 spec does not allow +/-25V to be applied
to the receiver input. Which an RS232 driver might well do. And in fact
there's no requirement (AFAIK) for the common mode range of the
differential input to include ground.
> <snip>
Connecting EIA-232 directly to EIA-422 could let the smoke
out of something, and we certainly wouldn't
want that.
ISTR that 422 was simply a balanced line version of 232. I think you
can just tie to the non-inverting line and ground and make it work.
It may work with Apple's so-called RS422, but that is so far from real
RS422 that I don't know how they got away with calling it that...
-tony
Peter Wallace
Mesa Electronics