Re: [NTLK] Newton (Fast) Serial Docking for newbies

From: Adriano (adriano.angelillis_at_gmail.com)
Date: Fri Jan 28 2005 - 16:20:39 PST


Peter,

your words explain why RS232 could transmit data at 230K, the same as a
RS422

As you know, RS-422 works on a binary (crossed pair in the cables)
communication, while RS-232 runs on a single data line,
this would explain why the entire process is more stable on this
protocol.

If i am wrong, please tell me more about it.

A big question is: why the TTL levels coming out from the Newton serial
channel3 literary burn the 5v shifted Max232 adapters connected on it?

Have you got any idea?

Adriano

Il giorno 28/gen/05, alle 23:10, Peter H. Coffin ha scritto:

On Fri, Jan 28, 2005 at 10:36:25PM +0100, Adriano wrote:
> Did you try to set the Keyspan speed in the Keyspan serial assistant
> 'Advanced settings' panel? It's available in OS 9. You could use it to
> have both the ports communicating at higher speeds (230K too), and you
> could also choose the port you prefer to use: printer or modem (labeled
> as 1 & 2 on the Keyspan adapter)

Note that 230k bits per second is exactly what Ron's "24Kbps" is in
bytes per second. 8 bits of data, 1 start bit, 1 stop bit = 10 bits -> 1
byte.

> The Keyspan adapter is a RS422 device, it should be faster and more
> stable than a RS232 device.

RS-422 differs from RS-232 PRIMARILY by allowing for a differential
voltage signalling instead of (only) referenced-from-ground signalling.
You run both at any bit rate your hardware supports, but RS-422 can go
FURTHER. In practical cases, that means a given cruddy cable may be able
to be run faster before start seeing data errors, but it's not magically
and inherantly and by-design faster in the same way that Firewire's
faster than Localtalk. Yes, "should be faster and more stable than
RS-232", but that may not mean what it sounds like you and Ron mean.

-- 
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is about cleaning up the fscking mess that results.
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This is the NewtonTalk list - http://www.newtontalk.net/ for all inquiries
Official Newton FAQ: http://www.chuma.org/newton/faq/
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