[time-nuts] Prologix GPIB/USB converter help...

John Miles jmiles at pop.net
Sun Apr 15 16:37:14 EDT 2007


An unpowered board will actually draw some current from the GPIB bus, via
the Atmel chip's protection diodes I'd imagine.  Enough to light the LEDs
dimly.  To avoid latchup concerns, it's probably a good idea to connect the
USB cable before the GPIB.

I don't see this happening on the newest board (version 4.20 firmware, with
the nice metal housing).  I've never actually seen it cause a problem, but
when troubleshooting, it's one possible thing to eliminate.

You can try sending the command ++rst to force the Atmel chip to cold-boot
itself.  That takes about 5 seconds.

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of John Ackermann N8UR
> Sent: Sunday, April 15, 2007 1:19 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Prologix GPIB/USB converter help...
>
>
> Just an update -- I have things working more-or-less OK now, after
> messing around with line terminations and timing.
>
> However, there *is* a problem, at least on one of my systems.  If you
> plug the adapter into the USB port with an active device on the GPIB
> side, things go nuts and that yields (at least with the Austron 2100F
> receiver I had on the bus) the
> every-character-typed-echoes-a-question-mark problem.  If I connect the
> USB first, then the GPIB, that problem does not occur.
>
> I haven't yet figured out if a device clear or interface clear command
> will correct that.
>
> John
>




More information about the time-nuts mailing list