Experimental Physics and
Industrial Control System

"Hu, Yong" <[email protected]> · Thu, 27 Sep 2012 16:49:16 +0000

Hello Kai,

I'm not sure if I completely understand your application. Anyway, here's my suggestions additional to Mark's.

1. Try compress record, see [1]: I suppose you have one record for "position" and another record for "current". Feed each of these records into one compress record to collect the data points you want (1000 to 10000values);

2. Try python-cothread for the curve fitting: data-fitting in C/C++ by subroutine or aSub record might not be easy. Another way to do fitting is to use Python (lots of data-fitting functions) combined with cothread (for channel access, see [2]). Since you're using Debian, there is a package at NSLS-II site [3] and you just need to install "python-cothread".    

Hope these help. Good luck!   

[1] https://wiki-ext.aps.anl.gov/epics/index.php/RRM_3-14_Compression

[2] http://controls.diamond.ac.uk/downloads/python/cothread/ 

[3] http://epics.nsls2.bnl.gov/debian/ 

Yong

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Mark Rivers
Sent: Thursday, September 27, 2012 10:47 AM
To: 'Kai Stein'; [email protected]
Subject: RE: How can I collect data values

The EPICS sscan record is designed for doing exactly this type of thing.  I will collect data into arrays in the record, and in conjunction with the saveData utility in the sscan module will write the values to a portable binary disk file.

Mark

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Kai Stein
Sent: Thursday, September 27, 2012 9:44 AM
To: [email protected]
Subject: How can I collect data values

Hello,

I'm working on an automatic data analysis of electron beam (emittance measurement with a wire scanner and a magnetic lens) with EPICS.
I get values from the hardware (self build measurement cards). The device support put the values into a longin records (this part is fixed, because it is already used for other applications).
I need to gather the values (will be a position and a corresponding
current) for a certain amount of time (approximately 1000 to 10000
values)  and then hand it over to a subroutine, to perform the analysis (like fitting a curve onto the data). It should all run on a debian machine.

My problem is to collect the data with EPICS. I thought about collecting them somehow in a waveform record, but i have no idea, how to do this by using other records instead of the device support.

Best regards,

Kai Stein

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System