Re: tds3000

["Nicholas P. DiMonte" <npd@aps.anl.gov>]

Heinrich,

The default TDS3000/5000 support is configured for 10k data points, as 
floats, for each waveform record. So each waveform only requires a 
little more than 40k bytes to be transfered. The 100k setting for 
EPICS_CA_MAX_ARRAY_BYTES from this support package is an over kill for 
this device. This setting only reflected the default setting at the APS 
control system. Since the release of this support, APS control system 
has increased this default setting to 140k to accommodate other control 
applications. So the very minimum setting for this support should be 
something like 42k for this environment variable. This should be more 
than enough for the preamble & data of each waveform. The setting of 
100k can be misleading, my apologies.

Regarding the blinking/flashing issue. I believe I have only seen this 
happen when the scopeAutoArmPrint sequence program was running. This 
program is only supplied as reference and was only used for single 
sequence acquire mode. I believe the program scans for an external 
condition before rearming the scope, but while it scans, it maybe 
resetting some scope settings, which may be causing the 
blinking/flashing. I just check a TDS5054 scope that does not have this 
sequence program installed and no blinking/flashing was observed. The 
scan rate was also set to .5 second.

Is this sequence program running on your IOC?

Nick DiMonte



Heinrich du Toit wrote:
> Hi
>
> I've compiled the tds3000 library. And connected it to a tds5000 scope.
> Works great.
>
> Just something that bothers me.
> It seem like the thing need to work with 100000 values in the array.
> Now firstly this seems to make anything more than .5 refresh rate
> impossible. Why is this? It's not like you can really plot 100K points?
> 1K would be more than enough.
>
> Plus if I put the MEDM screen in single display mode the whole thing
> would blink/flash a few times when it refreshes.
> I have accelerated nvidia - ubuntu setup so it's not the pc that's 2
> slow. It seem the thing redraws the screen about 20+ times everytime.
> Once again not needed I think. ?
>
> Most of all this is irritating and I can't go and put up a flashing
> scope display in the control room :) 
>
> I tried changing the 
> epicsEnvSet(EPICS_CA_MAX_ARRAY_BYTES, 100000)
> line in st.cmd
> But this seems to break the system completely :( Guess it's hard coded
> somewhere.
>
> If this can't be modified that's ok.
> I can work with multi-display and keep update rate 1 sec or slower.
> Was just wondering.
>
> Thanks
> -Heinrich
>
>
>