[time-nuts] Linux code for Prologix GPIB/USB

SAIDJACK at aol.com SAIDJACK at aol.com
Sun Feb 25 19:27:04 EST 2007

In a message dated 2/25/2007 22:20:09 W. Europe Standard Time,  
hmurray at megapathdsl.net writes:

I found  it also went into blinking-LED mode if I sent it another command too 
quickly and didn't have flow control working.  It works fine without  flow 
control as long as you pause before sending it another command.   At least 
what I'm doing.

Hi there,
I found the same thing. It's a bug in the Prologix firmware: a micro is  
connected to an FDDI (or similar) USB to RS232 (TTL level) converter, and the  
micro is extremely sensitive to anything sent over the RS232 TTL  interface.
Keep in mind that the USB is being used as a vehicle for the underlying  
RS-232 connection, so Baud-rates etc still apply, even over the USB.
That micro get's unhappy very easily and starts blinking, such as when  
commands are sent to it too quickly or the flow control is not right for some  
Once it blinks, it's kind of stupid and doesen't try to recover (after a  
time-out etc) - a hard-reset is needed to get it out of that mode.
I modified my board to have a true RS232 to GPIB connection, bypassing the  
FTDDI chip, and that was not easy due to this sensitivity of the Micro's  
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