Experimental Physics and
Industrial Control System

"Nicholas P. DiMonte" <[email protected]> · Tue, 03 Jul 2007 12:08:16 -0500

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

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System