Daun Yeagley wrote:
Hi David
You have hit on the exact reason the 5370 has a binary transfer mode. This mode
essentially transfers the bits directly from the counter hardware to the bus.
Remember this counter was designed and built quite a few years ago, and the
processor in it is rudimentary at best by today's standards. It took a *lot* of
time for it to format up the numbers into ASCII! I'm not sure if it was
specifically stated in the manuals, but it was a well known fact that to get any
speed at all, you had to use the binary format.
Daun
Thanks for that. It all makes sense now.
I had not thought about the processing needed on the 5370B - I was only
thinking about the amount of data transfered, and the overhead of the
additional calls to ibwrt and ibrd, and had not considered what the poor
old HP was having to do. Hence I could not understand why my program was
as slow as what it was. I could understand there would be some time
penalty, but not 250x slower.
I'll read the manual carefully on the binary format and use that
instead. Example 5 of the programs in the manual
http://www.g8wrb.org.uk/useful-stuff/time/HP-5370B/
(page 3-29) does refer to it as a "fast binary mode", so I guess it is
saying it's quicker than ASCII, although ASCII is the default.
I note the binary mode is only suitable for the +/- TI function. A
binary mode would be useful for frequency or period at gate times of
0.01 or 0.1 s, but I guess the HP 5370B would have to process the data
in those modes, so it would be no quicker than the ASCII.
It's time to go to be now, so I'll read about the binary mode in bed -
I'm sure it will send me off to sleep!! It does not look easy, as some
parts are in 2's compliment and others are not.
Given my SPARC processor is Big Endian, whereas the Intel format CPU in
Poul Henning Kamp's PC is Little Endian, it is perhaps surprising the
binary data could be read properly on my SPARC.
PS,
you may be aware I had some difficulty locating the Solaris drivers for
the GPIB board (National Instruments want more for them than I paid for
the GPIB board and the HP53270B put together!!) Converted to $US, the
drivers are around $750 or so.
The drivers were in Labview for SPARC, so that is how that problem was
solved.
--
David Kirkby,
G8WRB
Please check out http://www.g8wrb.org/
of if you live in Essex http://www.southminster-branch-line.org.uk/
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