17 Jun
2013
17 Jun
'13
9:50 p.m.
Every citation of the TIA/EIA/RS-232 spec talks about
the range of
voltages used for signaling, but I can't find a citation of "voltage
into what LOAD" defined.
It was something like 20 years ago that I read the spec; that memory is
a bit fuzzy. But I think the voltages specified are open-circuit
voltages, with limits placed on the effective series resistance.
RS?EIA?TIA-232 is a single-ended protocol, which makes
it less
tolerant to various signal issues, such as ground loops, induced
noise, etc.
True. But it also makes it simpler in various respects. If nothing
else, it approximately halves the signal pin count.
I remember that the old MC1488 driver were
power-hungry devices;
Let's not criticize the spec for the failings of one particular
implementation. Unless you have some reason to think this is
unavoidable, that any implementation of the spec will necessarily be
that power-hungry...?
'232 was a good interface for the 1960s and 70s,
but it's not a great
choice today.
Actually, I find it a great choice even today, for many tasks. (There
are, of course, also lots it's not a good choice for; for most of them, it
never has been - or never would have been.)
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