At 15:25 02/23/99 -0500, Darren Logan wrote:
>Is there such a thing as a MODEM CHIP ?, if so, where can I find out more
>about them. This could be interesting.

there are quite a few, and a simple 2400baud fsk modem probably isn't
expensive either (and they're pretty simple to implement, hardware-wise,
and software-wise too, if you know anything about modems and at commands).
check eg. rockwell. (there are a bunch of others, i just can't remember any
right now. look at the telecom sections of manufacturers.)

>I would imagine though, such a TRANSCEIVER chip would be expensive.

not necessarily. but it depends a lot on your data rate whether it makes
sense. for low data rates you don't have to modulate, you can just send the
ones and zeros on the road.

>Current loop - yes that's a possibility, although digital would be preferable.

i'm not sure, but i think wagner meant a digital current loop (at least
that's what i thought of when i read it :) : async serial data with current
loop driver, not an analog 4..20mA loop. is probably slower and safer than
rs 485.

ge