[aprssig] RE: MacAPRS + D7a

scott at opentrac.org scott at opentrac.org
Fri Dec 30 15:55:43 CST 2005

Not all USB/serial problems are Windows-specific.  The problem I have with
the OpenTracker and USB is that devices using bulk endpoints have absolutely
no latency guarantees.  Even if your converter properly carries all signals
to and from the serial device, things can still get really screwy in the
time domain.  You have to remember that USB is a host-driven, polled
interface.  Even if the device has data to send, it can't do anything except
wait for an IN token from the host.


From: aprssig-bounces at lists.tapr.org [mailto:aprssig-bounces at lists.tapr.org]
On Behalf Of Jason Winningham
Sent: Friday, December 30, 2005 12:09 PM
To: TAPR APRS Mailing List
Subject: Re: [aprssig] RE: MacAPRS + D7a

On Dec 30, 2005, at 12:54 PM, KC2MMi wrote:

Been trying to get my new D7 working with my new Powerbook.

I am using a

USB->Serial converter that shows up as /dev/tty.usbserial0 .

I'd MOST STRONGLY suggest that first you try using the radio with a Wintel

(sorry) that has a real hardware serial port on it. In the Wintel world we
see a

lot of problems caused by USB/Serial adapters that simply don't work 100%

properly. The fastest way to make sure that your cable & radio configuration

correct, is to try them on a machine that has a real serial port so that is

simply not an issue.

These usb/serial problems are largely confined to wintel boxes. If he were
trying to get it to work on a windoze box your suggestion has much merit,
but he isn't.

If the device has Mac OS X drivers, it's probably gonna work. I'm going to
go out on a limb and guess he's got a Keyspan device (because of the device
special file name), in which case he's in good shape. I rate a Mac with a
Keyspan serial adapter as being just as good as a wintel box with a hardware
serial port.

If you happen to have a computer with a real hardware serial port handy,
fine, go test with it, but I wouldn't go to a whole lot of trouble to get
one, especially if you haven't checked these things yet:

Other problems: Plain defective cables, even from Kenwood. Or pins2/3 cross
wired, triple check the pin outs and cables if they are home wired. Then
pins 2/3 and try again anyway, the diagrams and nomenclature are often

Yep, check all these things at least twice.

It would be terribly convenient if there was another ham in your
neighborhood with a working cable you could borrow for a few minutes.


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