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[aprssig] FOUND -NEW laptops for APRS with a Serial Port

Scott Miller scott at opentrac.org
Tue Apr 15 13:46:22 UTC 2008


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.

The OpenTracker's bootloader sends an ACK when it starts up, and expects 
an ACK back within something like 200 msec (used to be much shorter) to 
get into programming and configuration mode.  For some devices, that 
quick RX/TX turnaround is just too much.  Some also tend to discard 
bytes when switching baud rates, or perhaps the baud rate switch 
commands aren't synchronized with the data, so that when the bootloader 
and config program switch to a higher baud rate, one or more bytes get lost.

None of this is documented in the performance specifications of the 
converter chips, of course.  I've just had to work to change the 
behavior of the bootloader to allow for it as best I can.

Scott
N1VG

K7FTP wrote:
> The problem is that not all USB serial (RS-232) adapters are well 
> behaved. In addition, some laptops with built-in serial ports are 
> actually an internal USB to RS-232 converter.
> 
> Case in point - I work with a wide assortment of telecom devices (Avaya 
> PBX gear, Cisco routers and switches, and some really esoteric stuff).  
> I also interface to a Clifford alarm, Uniden scanner, and Kantronics 
> KAM-XL - plus programming interfaces for Kenwood and Icom radios.
> 
> I needed a laptop that would talk to all of these.  Plus I wanted a 
> Cardbus (PCMCIA) slot to use an EVDO device (Sierra AC595 for Sprint).
> 
> One of the local vendor techs has a Sony VAIO that his employer got for 
> him. It has an RS-232 port.  Several of the vendor-specific programs 
> don't like the RS-232 port in it.  Turns out that it is internally a USB 
> to RS-232 converter.
> 
> I have a Toshiba Tecra A9-S9015X.  It runs XP just like his VAIO, but 
> everything I have - including the same vendor-specific software - works 
> very well with it.  It is a real RS-232 port.
> 
> The Toshiba Tecra A9-S9013 is a similar system, but came with Vista 
> installed.  MS changed the way serial ports work under Vista, and the 
> Clifford alarm software does not work under Vista.  Put XP on that 
> A9-S9013 (or buy an A9-S9013X) and poof - everything works.
> 
> I had a chance to speak with the Toshiba program manager for laptops at 
> CES in January.  They appreciated hearing first-hand that the RS-232 
> port is not a waste of time.  It gives them an edge, the only other 
> systems that really have real ports are Dells, and the cost is higher.
> 
> I have been impressed with the quality, and I have put mine through 
> rough use.  I bought matching A9-S9015x units for my family.
> 
> Here is a review I wrote.  I really recommend the Tecra A9 units.
> 
> http://www.commtechreview.net/jeep/a9s9013.htm
> 
> 
> ----- Original Message ----- From: "Chuck Gooden" 
> <Chuck.Gooden at comcast.net>
> To: "TAPR APRS Mailing List" <aprssig at lists.tapr.org>
> Sent: Monday, April 14, 2008 6:10 PM
> Subject: Re: [aprssig] FOUND -NEW laptops for APRS with a Serial Port
> 
> 
>> Seems like it would be cheaper to use a USB to serial converter.  The 
>> expensive laptop will be obsolete very soon.
>> But its your money.
>>
>>
>> KENT HUFFORD wrote:
>>> Thanks to all that responded to my search.
>>>
>>> There seems to be lots of manufactures that make laptops with real 
>>> legacy
>>> serial ports.
>>>
>>> They just don't sell them at big box stores like Best Buy, Target, 
>>> Costco,
>>> RS, or Micro Center.
>>>
>>> Nor are they "consumer grade", that sell for around, or under $1,000.
>>>
>>> Dell, Toshiba, and HP/Compaq sell laptops with serial ports on their
>>> "business" upper grade systems. These are more expensive, have faster 
>>> CPUs
>>> (t9500), sometimes more HD space.
>>>
>>> I'm leaning between a M9 or a D830 for a laptop to do my APRS, HRD, 
>>> CS3 work
>>> on.
>>>
>>> Thanks again to all.... A great group
>>>
>>> Kent
>>> KQ4KK
>>>
>>> -----Original Message-----
>>> From: aprssig-bounces at lists.tapr.org 
>>> [mailto:aprssig-bounces at lists.tapr.org]
>>> On Behalf Of KENT HUFFORD
>>> Sent: Sunday, April 13, 2008 3:39 PM
>>> To: 'TAPR APRS Mailing List'
>>> Cc: michaelnewland at bellsouth.net; kathryn at agolden.com
>>> Subject: [aprssig] NEW laptop for APRS with a Serial Port?
>>>
>>>
>>>
>>> Most new laptops don't come with Serial Ports, and some not even a 
>>> PCMCIA
>>> slot.
>>>
>>> I am looking for a fast, new laptop (VISTA), (not a MAC) that has a 
>>> built-in
>>> SERIAL Port.
>>>
>>> I don't want to use a USB to Serial adaptors and such. Would like a 
>>> laptop,
>>> with a built-in serial port, also not have to add a port replicator or
>>> docking station to get it.
>>>
>>> So far, I have only found Toshiba Tecra A9 and M9's and DELL (business)
>>> D830s with a built-in serial port.
>>>
>>> Any body know of another mainstream laptop with serial ports so I can 
>>> run my
>>> serial port stuff, such as APRS?
>>>
>>> Thanks,
>>> Kent
>>> KQ4KK
>>> (no MAC's, no dongles, no adaptors, no port replicator, etc)
>>>
>>>
>>>
>>> _______________________________________________
>>> aprssig mailing list
>>> aprssig at lists.tapr.org
>>> https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
>>>
>>>
>>>
>>
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> 
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