[time-nuts] A Prologix GPIB-USB hint

Prologix support at prologix.biz
Sat Jun 9 11:10:01 EDT 2007


Thank you Paul for the hint! We shall add that to the help doc.

The upgrade that Didier mentioned will be ready for public release very soon
and will be posted on prologix.biz.

Regards,
Abdul

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Didier Juges
Sent: Saturday, June 09, 2007 8:02 AM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] A Prologix GPIB-USB hint

Poul,

This has been fixed in the most recent release. Abdul added a ++read command
that gets a single reading and then turns TALK off the instrument.

I have not actually tried it, but I have received it from Abdul a week or 2
ago.

The firmware isd easy to upgrade.

Give him a call.

Didier 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Poul-Henning Kamp
Sent: Saturday, June 09, 2007 9:32 AM
To: time-nuts at febo.com
Cc: sales at prologix.biz
Subject: [time-nuts] A Prologix GPIB-USB hint


I spent the better part of an afternoon trying to figure this bit out, so to
save somebody else the time:

Some GPIB instruments will complain if addressed to talk when they have not
been asked about anything.  The HP6626A Power Supply is my present instance.

The Prologix GPIB-USB has the "++auto" command which controls if it should
automatically go into listen after a talk, the description on the manual
page is:

	Enable (1) or disable (0) "listen-after-talk" feature

Based on that description, one would, or at least I would, expect the
behaviour to be that nothing happens until the next write, so that this
would work:

	++auto 0
				idle bus
	write something
				device= listen
				send data
				idle bus
	++auto 1
				idle bus
	write something
				device= listen
				send data
				device= talk
	read something


But that is not the case.  "++auto 1" puts the device in talk mode
immediately, so the sequence needs to be:


	++auto 0
				idle bus
	write something
				device= listen
				send data
				idle bus
	write something
				device= listen
				send data
				idle bus
	++auto 1
				device= talk
	read something

You've been warned :-)

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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