At 11:54 PM 31/01/1997 EST, you wrote:
[snip]
>
>I personally recommend the SN75176 RS422/485 chip from National
>Semiconductor.  It's a rugged little chip BUT will use considerable power
>when trying to drive signal a ways (and they will get hot).
To give credit where credit is due,  TI was the first out with the 75176 and
if you check out their rather thick Data Transmission Circuits Data Book you
will find many RS422 devices.
>
[snip]

>*I used bps and not baud - these two are not the same all the time.
>Starting with rates above 1200 bps, baud and bps are not the same.

I disagree!

Originally Baud (shortened from baudot) was used to describe the 5 bits
Baudot codes used by teletypes.  Then along came EBCDIC and ASCII and a baud
came to represent a 11 bit character; 1 start bit, two stop bits.  ie: 110
baud with two stop bits is considered to be the same speed as 110 baud with
one stop bit even though we all know that they aren't but in fact means 10
chars per second.  As speeds increased the second stop bit was dropped and
most software, although allowing a choice doesn't use it.  BTW, That is why
most UARTs have a 5 bit choice for character size.

The parity position is another spot where baud, or bps, are deceptive.  Most
serial devices can now insert a parity bit in addition to the 8 data bits
plus two stop bits for a total of 12 data bits per character.  In other
words,  if you are trying to determine actual characters per second you must
take into account the actual number of bits in a character.

So for all speeds, divide the baud rate by 10 to get the bits per second.
If you set number of bits to 8 and add two stop bits and insist on parity
the number of bits per character will increase and, therefore,  the
characters per second will decrease,  but the number of bits ber second is
still the same.

>
>I refer anyone wanting more info to The Modem Communication Book (don't
>have exact title or author cause that book is at work) for protocol info
>and National Semiconductors Communications Databook - good info on EIA
>and RS standards.
>--|
>--|
>--|  Troy Nelson   LinuxKing@juno.com
>--|
>--|
>
>
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with arrows in their backs.
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