View
55
Download
2
Category
Tags:
Preview:
DESCRIPTION
Creating an EPICS Based Test Stand Development System for the BPM Digitizer. Farah Memon San Jose State University SULI, Science Undergraduate Laboratory Internship August 12, 2010. Linac Coherent Light Source (LCLS). Provides m ovies of molecular activities . - PowerPoint PPT Presentation
Citation preview
Creating an EPICS Based Test Stand Development System
for the BPM Digitizer
Farah MemonSan Jose State University
SULI, Science Undergraduate Laboratory InternshipAugust 12, 2010
Linac Coherent Light Source (LCLS)
Provides movies of molecular activities.
X-ray pulses are short in wavelength.
Photon energy ranges from 540eV to 9.0keV.
Highest x-ray pulse energy is 3mJ.
Advances in medicine, chemistry, and materials science.
BPM Digitizer Beam Position Monitor (BPM) Digitizer is used to obtain the location
of the electron bunches in the LCLS. 4 different input channels capture signals from four different sides
of the beam. The signals are converted at a low intermediate frequency (IF). –
Radio Frequency (RF). The RF signals are digitized using analog to digital converters
(ADC). The Digitizer has four 16K by 18 bit buffers; one for each channel. The ADC acquires data at each rising each of the clock where the
external clock rate is 119MHz and internal clock rate is125 MHz.
BPM Digitizer
The process of acquiring RF signals and keeping them as digitized samples in the buffer.
Monitoring the Digitizer
The IOC is the VME 64x Crate with the Motorola Microprocessor.
Consists of EPICS Core and Application Database.
The OPI is a Dell Linux Machine (Service Tag: GGQXPDI).
Allows the user to view process variables on iocConsole or EDM (EPICS GUI).
Controlled using an IOC (Input/Output Controller) and an OPI (Operator Interfaces)
LAN
Monitoring the Digitizer
Example of a record:
record(waveform, "$(digi):WAV"){
field(DESC, "Raw VMEDIGI Data")field(DTYP, "VMEDigi-Waveform")field(INP, "#C$(card)S0@")field(FTVL, "SHORT")field(EGU, "Counts")field(HOPR, "32768")field(LOPR, "-32767")
}
Each field of a record is called a Process Variable (PV).
Project Guidelines
Matlab is currently used to test the digitizer with Matlab Guide being the GUI.
Similar as well as advanced functionalities need to be transferred over to EPICS to develop an improved test stand development system.
All the previous functionalities need to be provided.
Added functionality of logging of data also needs to be incorporated.
The GUI for Matlab Scripts
The Matlab Guide providing the existing functionalities.
Setting up Equipment
Hardware Equipments: Power-One Hybricon VME
64x crate with VME 64100 Microcontroller in Slot 1 and the BPM Digitizer in Slot 4.
Cisco Systems Catalyst 3750 Series Switch
Digi Port Server TS 16 serial port
HP Signal Generator (Model 8648C
Stanford Research Systems Digital Delay Generator (Model DG645). Power-One Hybricon VME 64x crate, Cisco
Systems Catalyst 3750 Series Switch, and
digi Port Server TS 16 serial port below.
Equipment
HP Signal Generator (Model 8648C) below.
Stanford Research Systems Digital Delay Generator (Model DG645) above.
Driver Code:R5-3-0 of BPM Application Code was used.
Simulation functions of the driver code were neglected.
Functionalities by the driver code
The following EDM Panel was provided with R5-3-0 vmeDigi driver code
Implementation in EPICS
genSub Record employed for illustrating the four different waveform signals.
The genSub module was incorporated into the IOC. The record allows easy passage of PVs as inputs. The genSub record was invoked periodically and
called a subroutine, written in C language, to perform division of the combined waveform signal.
In the subroutine, the genSub record is passed as a pointer to a structure.
The outputs of the function, the four distinct input signals, were displayed onto the EDM panel.
Displaying four waveforms
Implementation in EPICSThe four input signals are clearlyillustrated on the main EDM panel.
Implementation in EPICSMathematical Calculations
waveProc1-0 module was incorporated with the existing source code.
Four instances of waveAnl records are added. Each waveform is passed as an input to the
record. The mathematical and statistical data relevant
to the waveform are contained in the PVs. All the PVs are exposed on the Wave Analysis
Record panels. These panels are attached to the main EDM panel via a button.
Implementation in EPICSThe Wave Analysis Record panel is linked to the main EDM panel.
Implementation in EPICSFast Fourier Transform
Matlab labCA is utilized. Matlab Client intefaces with the IOC through
Channel Access and has access to the PVs. Matlab is used to perform the fast Fourier
transform (FFT) and compute the power spectrum of the four waveforms. The program also finds the carrier frequency.
Matlab labCA commands obtain the waveform signals and change the contents of the four power spectrum signals.
The four power density signals are displayed on a separate EDM panel and linked to the main panel via the button ‘FFT’.
Implementation in EPICSThe FFT EDM Panel displaying the power density of he four waveform signals with respect to the frequency.
Implementation in EPICS
Logging functionality
Six different files created for logging: Four files for the RF signals from four
input channels. One file for the combined waveform. One generic log file for hardware-specific
information, i.e, serial, firmware, and hardware revision number.
Files are created on demand – upon a click of a button
For data corresponding to waveforms, a function in the wavAnl record was written.
For the generic log file, a subroutine was created.
Implementation in EPICSLogging functionality – waveform log files
Implementation in EPICSLogging functionality – generic log file
Future Work
Add buttons that bring up PDF files that assist the user in configuring the BPM digitizer.
Ability to change between engineering units; currently the default units are ‘samples’.
For example: going from samples to volts. The test stand system can be used as a template to
design test stand systems for other types of digitizers, including the PAD digitizer.
References[1] J. Frisch et al. Beam Position in LCLS [Online]. Available: http://www.als.lbl.gov/biw08/papers-final/MOIOTIO02.pdf[2] LCLS FAQ [Online]. Available: https://slacportal.slac.stanford.edu/sites/lclscore_public/Lists/LCLS_FAQ/FAQ.aspx[3] R. Lill et al. Design and Performance of the LCLS Cavity BPM System[Online]. Available: http://accelconf.web.cern.ch/accelconf/p07/PAPERS/FRPMN111.PDF[4] W. Ross, “SLAC BPM Digitizing Module 144-045-1 Programming Module” [5] (2008, March 10). EPICS I[Online]. Available: https://confluence.slac.stanford.edu/download/attachments/67503315/LCLS-EPICS-Intro.pdf?version=1&modificationDate=1257093082000[6] B. Dalesio. (1999). Channel Access Concepts [Online]. Available: http://www.slac.stanford.edu/comp/unix/package/epics/training/documents/02_CA_Concepts.pdf [7] A. Foster. (2003, March 12). The EPICS genSub Record Reference Manual [Online]. Available: http://www.slac.stanford.edu/grp/ssrl/spear/epics/site/genSub/genSubManual.pdf[8] E. Norum. WaveProc [Online]. Available: http://www.aps.anl.gov/epics/modules/soft/waveProc/index.html[9] E. A. Medvedko et al. LCLS Stripline BPM System Commissioning [Online]. Available: http://trshare.triumf.ca/~pac09proc/Proceedings/papers/th6rep036.pdf
Recommended