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Re: Solving the need for ISA or USB slots and Serial Ports

Do you mean TCP?  IP isn't necessarily guaranteed for delivery either.  
Although, you're right, either the node will need to be smart enough to 
be able to prevent damage if the start command goes through and the 
stop command doesn't.  Although, what I was thinking of for rotators 
was more of a servo loop control, where the computer would send out a 
specific "setpoint" value, fed to the rotor servo as voltage, current 
loop, what have you, and the rotor would automatically track that 
setpoint and not need separate "start" and "stop" commands, just a 
single write and latch operation into a DAC.

I know most rotators today don't do it that way, but I've been thinking 
for years that it's time they did .. simpler control and less chance of 
runaway operation.  It's simple enough to do nowadays .. three wire 
interface with DC power, ground, and setpoint voltage .. and you can 
even limit the input voltage with simple op amp circuits so if a short 
somewhere drives the input to one rail or the other the rotator will 
still not end up grunting against the stop.

Yeah, I know, I'm being an armchair engineer, but it's worth thinking 
about, since basically it's a gear reduction DC motor, a position 
sensing pot, and some op amp circuitry with maybe a few MOSFET driver 
bridges added in.  Definitely feasible in this day and age, and would 
integrate very nicely with a LAN-based station control system ..

On Wednesday, Jul 2, 2003, at 13:59 US/Central, Don Woodward wrote:

> UDP is not guaranteed for delivery whereas IP is - do you really want 
> your
> rotator to be commanded to be moved without ever receiving a "stop"
> command? Of course the limit switches would kick in but it could
> potentially over-use some of these rotators which are not designed for
> constant use.
> Or even worse a TX command to key your radio without a unkey?
> 73's
> Don Woodward
> AMSAT 33535
> kd4app@amsat.org
> http://kd4app.webhop.org
> ----- Original Message -----
> From: "Bruce Bostwick" <lihan161051@earthlink.net>
> <snip>
> My vote goes with TCP/UDP over IP, hands down.  There are way too many
> out of band protocols running around on LAN's as it is, and not all
> switches or routers deal with those gracefully.  I have painful
> <snip>
Heard from a flight instructor:
"The only dumb question is the one you DID NOT ask, resulting in my 
going out and having to identify your bits and pieces in the midst of 
torn and twisted metal."

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