[time-nuts] PTS D310 and GPIB

Rex rexa at sonic.net
Mon Aug 3 12:28:48 UTC 2009


GandalfG8 at aol.com wrote:

> 
>In a message dated 03/08/2009 10:39:55 GMT Daylight Time, rexa at sonic.net  
>writes:
>
>Manuals  for other PTS units posted by GandalfG8 <Nigel> on Didier's 
>pages  got me started -- thank's guys. The D310 should be able to 
>generate  frequencies to 0.1 Hz resolution. I haven't figure out how to 
>set it  beyond 1 Hz resolution. The 'F' command sets the frequency. I 
>assumed I  would just give it one extra digit for the extra resolution, 
>but that  doesn't seem to work.
>
>
>
>---------------
>Hi Rex
> 
>Glad to hear the manual was helpful:-)
> 
>I'm not familiar with the D310, aware of it but never seen one,  but the 
>basic PTS310 is only specified to 1Hz resolution so would have  expected the 
>D310 to probably be the same.
> 
>The PTS310 is the only one of the lower frequency units, ie below 1GHz,  
>that doesn't have 0.1 Hz as an option but it's also the only one that offers  
>it's finest resolution by default.
> 
>Whereas the other units use a series of identical optional plug ins to  
>provide the 10KHz to 0.1Hz steps, the PTS310 uses a digital synthesis  module 
>for the finer resolutions so always goes to 1Hz but doesn't, as far  as I'm 
>aware, have any option to extend beyond that.
> 
>regards
> 
>Nigel
>GM8PZR
>
>  
>

Thanks for the quick feedback. I think I have just figured out how to 
talk to it by trial and error.

 From my digging around in the last few days, it seems that the design 
of the two sections in the D310 are not too much like the 310. It looks 
more like the 500 or 3200 without the final stages. For instance the 
reference frequencies in the regular 310 come from one SGC module, 
whereas the D310 uses SGA and SGB. I was surprised when I found that the 
D310 used different strategies than the 310.

So it is a bit different and if you look at the datasheet for the D310, 
the 0.1 Hz resolution is standard. I certainly expected the 310 and D310 
to be based on the same design, but they aren't.

Now, back to the GPIB commands. Looking at the GPIB section in the PTS 
500 manual, it appears that it uses the command format that I expected. 
For the extra .1 digit, just add one more digit in the 'F' command. So 
where did I go wrong?

Seems the manual is not quite right in its examples. I was stringing 
commands together like 'f1234567a0[LF]', the a0 being command for max 
output level. That's what the manuals show in an example or two, but 
seems the hardware gets confused if there is more that 1 command with 
just 1 LF at the end. I think 'f1234567[LF]a0[LF]' is ok.

If I send it just 'f1234567[LF]' I get 123456.7 Hz, which is what I 
expected. With 'f1234567a0[LF]' I get 1.234567 MHz. So it seems the 
controller wants a LF after each command to not get confused.

There may be some finesse points I haven't worked out yet, but I'm on 
the right track now.





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