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[aprssig] FOUND -NEW laptops for APRS

Alex Carver kf4lvz at yahoo.com
Tue Apr 15 19:22:12 UTC 2008


> Message: 23
> Date: Tue, 15 Apr 2008 06:46:22 -0700
> From: Scott Miller
> Subject: Re: [aprssig] FOUND -NEW laptops for APRS
> with a Serial Port
> To: TAPR APRS Mailing List <aprssig at lists.tapr.org>
> Message-ID: <4804B1AE.8030307 at opentrac.org>
> Content-Type: text/plain; charset=ISO-8859-1;
> format=flowed
> 
> One problem I run into frequently with USB-serial
> adapters is that some 
> have a lot of latency.  They can handle high baud
> rates, but there's no 
> guarantee that those bytes get into or out of the
> device in a timely 
> manner, mostly because of the polled nature of USB.


For those of us that have lots of devices sitting near
a regular computer (not necessarily a laptop) I highly
recommend the Ethernet to serial hubs that are
available over trees of USB ports.  I have one at my
lab that works very well.  This is not a cheap
solution by any means but it does provide many true
serial ports with very low latency and is supported in
all three operating systems (Windows, Mac, and Linux).
 In all cases, using the drivers for the hub the ports
show up as virtual serial ports.  In this
configuration, the device doesn't require an IP
address either.  If you do give it an IP, you have the
option of using telnet connections to exchange data. 
For the particular unit I have, made by Comtrol, each
port can be switched between RS232, RS422, and RS485
and all ports support up to 192kBaud.

The particular unit I have happens to use DC power
input (with an external brick) so there's a potential
for mobile use.  There are also small units available
with 1, 4, or 8 ports (I have a 32 port).


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