1. Using EPICS for Beamline Control and Data Acquisition
Mark Rivers
GeoSoilEnviroCARS, Advanced Photon Source
University of Chicago

2. Acknowledgements
Many slides borrowed from the “Getting Started with EPICS” lecture series held over past year at APS. All talks are online
Ned Arnold, APS, Introduction to EPICS
Ken Evans, APS, MEDM
Tim Mooney, APS, Beamline controls

3. Outline Goals for Beamline Control and Data Acquisition (BCDA) systems
Brief Overview of EPICS
Advantages of using EPICS for BCDA
Where is EPICS being used for BCDA today
What’s available for EPICS BCDA
The synApps module from APS
Cover some basics today
More details in talks on detectors, feedback tomorrow
What needs to be done

4. Characteristics of an Ideal Beamline Control and Data Acquisition System
Easy to use
Intuitive Graphical User Interface (GUI)
Customized for the specific experiment
Fast, efficient
Expert users don’t want to navigate GUI
Powerful, able to accomplish any task, even if it has never been done before
Able to use existing applications that have substantial development and user familiarity (Blu-Ice, SPEC, Photon Factory EXAFS program, etc.)
Can use different applications to run the same equipment for different experiments (i.e. not tied into Labview or SPEC drivers)
Available off-the-shelf, no development required (you wish!)

5. Introduction: What is EPICS?
A collaboration of the controls groups of many research organizations that use the EPICS tool-kit.
A distributed architecture that supports a wide range of solutions from small test stands to large integrated facilities.
A set of tools that reduces software application and maintenance costs by providing:
Configuration tools in place of programming
A large installed base of tested software
A modular design that supports incremental upgrades
Well defined interfaces for extensions at every level

6. What is EPICS? A Collaboration A Control System Architecture
Network-based “client/server” model (hence the EPICS logo) CA CA
Client
Client CA CA
Server
Server
For EPICS, client and server speak of their Channel Access role
i.e. Channel Access Client & Channel Access Server

7. * A Process Variable (PV) is a named piece of data.
What is EPICS?
Channel Access clients are programs that require access to Process Variables to carry out their purpose
StripTool
MEDM
CAC
CAC
CAS
Process
Variables
CAS
Process
Variables
The “service” that a Channel Access server provides is access to a Process Variable*
* A Process Variable (PV) is a named piece of data.

8. What is EPICS? Process Variable
A Process Variable (PV) is a named piece of data associated with the beamline (e.g. status, readback, setpoint, parameter)
Examples of PV names and values:
13IDA:cc4 3.2e-08 torr (Cold cathode gauge 4)
2IDA:m1.RBV mm (Motor 1 actual position)
13IDA:MonoEnergy keV (Mono energy set point)
S:SrCurrentAi mA (APS ring current)
APS:Mode ‘Stored Beam’ (APS storage ring mode)
13IDC:mca1 {0, 0, 1, 1, 1, 102, 210, 262, 0, 0, …} (MCA spectrum)

9. What is EPICS? Process Variable
A Process Variable is a named piece of data with a set of attributes
Examples of Attributes:
Alarm Severity (e.g. NO_ALARM, MINOR, MAJOR, INVALID)
Alarm Status (e.g. LOW, HI, LOLO, HIHI, READ_error)
Timestamp
Number of elements (array)
Normal Operating Range
Control Limits
Engineering Unit Designation (e.g. degrees, mm, MW)

10. What is EPICS? A Control System Architecture
Network-based “client/server” model where the basic data element is a Process Variable
The Channel Access Protocol defines how Process Variable data is transferred between a server and client
The entire set of Process Variables establish a Distributed Real-time Database of machine status, information and control parameters
Process
Variables
CAS
Process
Variables
CAS
Process
Variables
CAS
Process
Variables
CAS
Process
Variables
CAS
Process
Variables
CAS
Process
Variables
CAS

11. My Special Data Collection Program My Accelerator Simulator Code
What is EPICS?
My Special Data Collection Program
Any tool/program/application that abides by the Channel Access protocol could be described as “EPICS Compliant”.
StripTool
MEDM
CAC
CAC
CAC
EPICS can be viewed as a “toolkit” of EPICS compliant programs. One can select the appropriate tool for their need or develop their own.
My Accelerator Simulator Code
(PVs)
CAS
CAS
iocCore
(PVs)
CAC
LabView
(PVs)
CAS
CAC

12. Typical Realizations of an EPICS System
Driving a motor with EPICS
circa 1995
circa 2002
IOC
CAS
IOC
Commercial Instruments
Custom Chassis/Panels
Technical Equipment

13. Channel Access in One Slide
“connection request” or “search request”
“get” or
“caGet”
“put” or
“caPut”
“set a monitor”
Who has a PV named “S1A:H1:CurrentAO”?
Change its value to 30.5
Notify me when the value changes
What is its value?
Channel Access Client
CA Server
CA Client
Channel Access Server
I do.
25.5 AMPS
OK, it is now 30.5
It is now 20.5 AMPS
It is now 10.5 AMPS
It is now AMPS
Process Variables:
S1A:H1:CurrentAO
S1:P1:x
S1:P1:y
S1:G1:vacuum
“put complete”
“post an event” or
“post a monitor”
30.5 is too high. It is now set to the maximum value of 27.5. or
You are not authorized to change this value or

14. IOC Software in One Slide
Network (Channel Access)
[IOC Software]
EPICS “iocCore” services and routines [EPICS-supplied]
Application Specific Database [of Records]
Record
Record
Application Specific Programs
[e.g. State Notation Language]
Record
Record
Record
Record
Record
Record
Record
Record
Record
Record
Record
Record
Record
Record
Record
Record
Record
Record
Device/Driver Support [EPICS-supplied/user-extensible]
New Device Support
“Supported” Instruments
“New” Equipment
“Supported” Instruments
“Supported” Instruments
“Supported” Instruments
Shared/Provided
Required
Optional

15. Standalone CA Clients (from EPICS Website)
ADT: Array Display Tool
ALH: Alarm Handler
AR: Data Archiver (the original, deprecated)
BURT: Backup and Restore Tool
CAEX: Channel Access Examples
CASR: Host-based Save/Restore
CAU: Channel Access Utility
Channel Archiver (SNS)
Channel Watcher (SLAC)
DM2K: Display Manager 2000 (BESSY)
EDD/DM: Editor and Display Manager (LANL)
EDM: Extensible Display Manager (ORNL)
HistTool: Data Histogramming Tool
JoiMint: Java Operator Interface and Management INtegration Toolkit (DESY)
Jprobe: Java Version of Probe, a Channel Monitoring Program
MEDM: Motif Editor and Display Manager
Probe: Motif Channel Monitoring Program
StripTool: Strip-chart Plotting Tool
Yviewer: Data Visualization Tool

16. EPICS Programming/Scripting/Display Languages
C, C++
tcl/TK
Visual Basic
Labview
IDL
Python
JAVA
Matlab
Unix shells
Any other language with the ability to call C functions in a shared library or DLL

17. Key Features of IOC software …
Two primary application specific components:
The real-time database of records (required)
State Notation Language programs used to implement state oriented programs (finite-state machine)
Machine status, information and control parameters are defined as “records” in the application specific database.
The data within a record is accessible via Process Variables.
Records have some functionality associated with them (scaling, filtering, alarm detection, calculations, etc). Different record types have different functions and uses.
Records are frequently associated with I/O equipment that requires unique “device support” for that instrument.

18. Ten really neat things about EPICS
It’s free
It’s Open Source
There are lots of users
All a client needs to know to access data is a PV name
You can pick the best tools out there …
… or build your own
The boring stuff is already done
A good contribution becomes internationally known
By following a few simple rules, you get a lot for free

19. Ten really neat things about EPICS for BCDA
There are lots of beamlines using it (next slide)
Most record types for beamline components and common operations already exist
Motors, monochromators, multi-channel analysers, A/D, D/A, digital I/O, scanning, save/restore, save_data, etc.
Lots of device support and drivers for commercial devices in these classes already exists
There are high-level applications available for free (e.g. EXAFS) or commercially (e.g. SPEC)
There is a lot of expertise available close by because Australian Synchrotron accelerator will use EPICS
You can have a basic beamline up and running very quickly with supported hardware, add features as time permits
I converted 4 NSLS beamlines from CAMAC/VMS to EPICS in less than 1 week

20. Synchrotron Beamlines Using EPICS
Almost all beamlines (> 30) at the Advanced Photon Source
Growing number of beamlines at NSLS (>10)
All beamlines at the Swiss Light Source (?)
Probable for beamlines at Diamond
Canadian Light Source (just beginning, not using APS beamline code)
A few beamlines at the ALS at Berkeley (?)

21. EPICS Software Architecture for I/O Control
Client Tool
CA Client
CA Server
DB Common
Record Support
Device Support
Driver Support
Optional
IO bus
Hardware device

22. Record Support Provides implementation for a record type
Lots of records come with standard EPICS
Some have been added in the synApps beamline control package
Example records
ai (analog input, .VAL field is single number)
ao (analog output, .VAL field is a single number)
motor (lots of fields, e.g.)
.VAL = target position
.RBV = readback position
.VELO = desired velocity
.DMOV = done moving flag
MCA (multichannel analyser, lots of fields, e.g.)
.VAL = histogram array
.PRTM = preset real time
.STRT = start acquisition when set to 1
.ACQG = acquire busy flag

23. Overview of synApps
A collection of EPICS applications for synchrotron-beamline users. Collaboration between APS BCDA group and other beamlines at APS and elsewhere
EPICS modules and build/configuration tools:
Modules: autosave, calc, camac, ccd, dac128V, dxp, ip, ip330, ipUnidig, love, mca, motor, optics, quadEM, sscan, std, vme, xxx
Build/config: config and utils directories
160,000 lines of code (C, SNL, databases), hundreds of medm screens
Related clients, libraries, and visualization tools:
IDL: scanSee, mca display, ezcaIDL, ezcaScan, ez_fit, HDF translator/browser, Ascii-format plotter, image processors, etc.
CA-Server based CCD control

24. synApps modules Modules contain the following kinds of support:
Compiled code; libraries
E.g., record and device support
State-Notation-Language programs
EPICS databases and autosave-request files
A database is a program written in a high-level language.
One or more copies of a database can be run, each with its own private variables (PV’s).
The database designer recommends PV’s to be autosaved by naming them in a .req file; you can override with a private copy of the file.
MEDM-display files
The default user interface
Documentation

25. Other EPICS modules used by synApps
asyn (driver/device support)
ipac (Industry Pack support)
seq (State Notation Compiler)
genSub (General subroutine record)
vxStats (IOC statistics)
allenBradley (PLC support)

26. autosave module
Records latest values of selected EPICS PVs; restores those values when the ioc restarts.
not an archiver; only the latest value is saved
not the same as saveData, which writes scan data
When a list list of PV’s is saved, the entire list is written, even if only one PV has changed.
Can save/restore any scalar or array-valued PV

27. ...autosave module
PV lists can use include files (e.g., <database_name>.req), include path.
Database developer can supply default include file with database.
User can override with custom include file.
Save triggers:
on change of any PV in the list
periodically
on change of a trigger PV
manual
User can reload save sets.
User can choose to save redundant filesAutosave reports status via EPICS PV’s

28. calc module
Support for evaluation of string or numeric expressions entered at run time (or at database-configure time)
Records
sCalcout – like calcout, but also supports string expressions; user can specify wait-for-completion.
swait – like calcout, but uses recDynLink (no “PP MS” link attributes)
transform – like 16 calcout records that share a PV data pool
Other code
string-calc engine
sCalcout soft device support (with wait-for-completion option)
interpolation routines for genSub record
(yet another) averaging routine for sub record

29. ccd module Support for area detectors (CCD’s and image plates)
Supported devices
MAR 165 CCD
MAR 345 image-plate reader
Roper (all WinView-supported CCD’s, including former Princeton and most former Photometrics devices)
Bruker SMART CCD
Can control, at minimum
exposure time
file name
data-acquisition start
wait for acquisition to complete
much more for most devices
Details in talk tomorrow

30. dac128V module
device support, database, and MEDM displays for dac128V IndustryPack module
8-channel, 12-bit DAC
Support exists to run a DAC channel manually, or according to an algorithm written at run time, or as a scan positioner, or as part of a PID feedback loop.
Good model for D/A converter support, even if you use different hardware

31. dxp module
record, device support, databases, and MEDM displays for XIA DXP and Saturn spectroscopy systems
dxp record for setting DXP parameters
device support for the mca record
More details in talk tomorrow

32. ip module
device support, SNL code, databases, and MEDM displays for many message-based devices
Supports lots of benchtop RS-232/GPIB instruments, e.g.
Keithley multimeters
Stanford Research Systems current amplifiers
MKS ion gauge controllers
Physical Instruments ion pump controllers, TSPs
Lakeshore temperature controllers …
deviceCmdReply
Used to write support at run time for one command/reply message
sCalcout to format output string
asyn record to write/read device
sCalcout record to parse reply
devXxStrParm device support
Generic support for many record types (ai, ao, bi, bo, etc.) with message based devices

33. ip330 module
device support, databases, and MEDM displays for the IP330 ADC IndustryPack module
16/32 channel, 16-bit ADC
ip330Scan for periodic, averaged reads of ADC channels
ip330Sweep, with the MCA record, for using ip330 as a waveform-digitizer
ip330PID for using the ip330 in a fast-feedback loop
Good model for A/D converter support, even if you use different hardware

34. ipUnidig module
device support, databases, and MEDM displays for the IPUnidig digital I/O IndustryPack module
Interrupt can call any driver, which is useful for devices that do not have interrupts themselves
Good model for digital I/O modules, even if you use different hardware

35. mca module
Support for multichannel analyzers, multichannel scalers, and other array-valued detectors
mca record
device support
Canberra 556 AIM module (MCA and ICB controller)
DSA-2000 Ethernet MCA
various Canberra-ICB modules for spectroscopy
SIS 3801 (Struck STR7201) MCS
(DXP support in dxp module)
(IP330 support in ip330 module)
(quadEM support in quadEM module)
More details in talk tomorrow

36. motor module Motor record and device support
Motors are the single most important component of beamline control
Provides:
stepper and servo motors
VME, CAMAC, RS-232, GPIB, Ethernet controllers
More than 20 types at present
soft-motor support
Put motor “face” on, e.g., a DAC channel
Drive a hard motor through a nonlinear transform of 1 or more real motors
user/dial/raw coordinates
backlash-takeout algorithm
pre/post move commands
many more features

37. optics module Slits and mirrors Monochromators
Four virtual positioners; two real motors
Automatic sync to motor positions
Completion reporting
Monochromators
Nondispersive double-crystal
Geometries: (Y1, Z2), (Y2, Z2)
Crystal species: Si, Ge, Diamond, Si (77K)
Miller indices, allowed reflections
Operational modes:
Use/Set
Manual/Auto
Managing the vertical beam offset

38. …optics module …Monochromators Spherical grating
Geometrical variables:
1) Grating line density; radius
2) Tangent-arm length
3) Diffraction order
4) Input/output slit distances
Operational modes:
Use/Set
Manual/Auto
Grating-stripe list
Manual sync to motor positions

39. …optics module Optical table
Table record supports a six-degree-of-freedom optical table.
User/client can write either to (x, y, z, qX, qY, qZ), or to underlying motor records.
Table rotates about user-specified point.
Table database includes a list of rotation points, selected by menu.
Can recover table position from motor positions
Partial support for fewer than six degrees of freedom

40. …optics module Optical table Geometries - Calibration/sync
SRI
GeoCARS
Newport
PNC
SRI
GEOCARS
PNC
NEWPORT
- Calibration/sync
Use/Set – changes to [X, Y, ..]. move table / change calibration
Zero – redefine current [X, Y, …] as zero
Sync – update [X, Y, …] from motors, honoring calibration
Init – clear calibration and sync to motors
Table record sets motor speeds so that motors start/stop together.

41. sscan module Support for user-programmable data-acquisition
sscan and busy records
saveData
recDynLink
A one-dimensional scan:
Do NPTS times:
Set conditions e.g., move motors; wait for completion
Trigger detectors e.g., start scaler; wait for completion
Acquire data read detector signals; store in arrays
Write data to NFS file
Multidimensional scan:
Same as a 1-D, but detector trigger executes inner-loop scan.
saveData monitors a set of sscan records, determines scan dimension when scan starts, and writes data as it is acquired.

42. sscan module

43. ...sscan module scan features:
Three 1-D scan types: constant-step-size, table-driven, fly
Unlimited number of data points, scan dimensions
0-4 positioners, 0-4 detector triggers, 0-70 detector signals
Acquisition from scalar and 1-D-array-valued PV's
Detector/client wait, data-storage wait
Pause/resume, abort
Double buffered: can write 1-D acquired data during next 1-D scan
saveData writes self-describing XDR-format (“.mda") files to NFS-mounted disk (vxWorks only, at present).
A positioner can have private scan parameters (scanparm record).
After-scan actions include move to peak, valley, and edge.
scanparm record + after-scan action = automated 1-D alignment, so you can easily implement an “Align” button.

44. …sscan module The sscan record performs 1-D scan
before-scan link – optional completion callback
positioner: any writable, numeric, scalar PV (menus, enums are ok)
detector trigger: any writable, numeric, scalar PV
detector signal: any readable, numeric, scalar or 1D array PV
array detectors: exactly <scanRecord>.NPTS elements are acquired
array trigger: callback indicates array data are ready to read
after-scan link – optional completion callback
pause/resume
abort (<scanRecord>.EXSC -> 0) wait for callbacks, cleanup
kill (two aborts in a row) abandon callbacks
handshake with multiple display / data-acquisition clients
handshake with data-storage client

45. Other data-acquisition-related software
Data-visualization tools for use with synApps
Run-time look at scan data
Offline tools for data-file manipulation
Supports 1-3 dimensional data
Distributed independently of ioc software
See lecture “Data Visualization.”
CCD data-acquisition tools
CCD module (see lecture “Detectors and Feedback”)
Portable CA Server based CCD support, and related software
Both of these solutions allow an EPICS CA client to drive data acquisition.
Both support ca_put_callback(), as required by the sscan record.

46. std module Epid record Scaler record String-sequence record
Extended PID record – more details tomorrow
Scaler record
Controls a set of counters with a common clock, gate, and trigger
String-sequence record
Like the seq record in base, but works for strings and numbers
Can choose to wait for completion after each step in sequence
Soft-motor database
Run-time programmable soft-motor/transform/hard-motor database
Quick solution for driving a motor through a nonlinear transform
Timestamp record [SLAC]
needed by SNS’ vxStats; currently not available in a module
4-step database
Up to four steps of (set condition; read data) with an end calculation
Originally developed for dichroism experiments

47. vme module VME record Device support for VME hardware, includes:
Provides run-time access to VME bus
Great for testing hardware
Run-time programmed control of an unsupported VME board
Device support for VME hardware, includes:
Joerger scaler
APS bunch-clock generator
APS machine-status interface
Heidenhain encoder interpolator
Generic A32 VME interface
HP Laser interferometer
VMI bit DAC
Acromag bit digital input

48. xxx module Prototype user directory Two ways to use this module
Builds everything in synApps into a load module
Contains command files to load/configure everything in synApps
Contains sample top-level MEDM-display file
Contains sample script to set environment variables and start up the sample user interface
Contains table of recommended address/interrupt configuration for selected VME and IndustryPack hardware
Two ways to use this module
Make copies; run changePrefix; build; customize; run a beamline
this is the recommended use
detailed instructions in support/documentation
2) Reference/grab bag

49. Single-crystal energy dispersive diffraction at high pressure
A Couple of Anecdotes
Single-crystal energy dispersive diffraction at high pressure
Good programmer, EPICS novice, IDL novice
Wanted to write code to collect single-crystal Laue diffraction with area detector, then rotate sample to put Laue spots into energy-dispersive detector
Got job done in weeks, amazed how easy to move motors, trigger CCD detector, read energy-dispersive detector MCA spectrum. He could concentrate on scientific problem
It runs at APS and at NSLS, since they both use EPICS, motor record, mca record

50. Stress/strain measurements at high-pressure
A Couple of Anecdotes
Stress/strain measurements at high-pressure
Novice programmer, EPICS novice
Wanted to script a common operation that was keeping users at beamline overnight
Remove slits, install imaging CCD detector, take strain CCD image
Install slits, remove imaging CCD detector, take diffraction CCD pattern with diffractio CCD detector
Repeat above hundreds of times
Got job done in an hour, amazed how easy to move motors, trigger CCD detectors, saving data to user-specified file names, etc.

51. Some Advice
Put the functionality in the server, resist the temptation to put it in the client if possible
Then any client can use it, not just your favorite client du jour
Purchase devices that already have support if they will meet the need. Resist temptation to save a few $$ on hardware if it means debugging a new device.
Check on to see if the work has already been done

52. Quick Summary of EPICS for BCDA
Advantages
Distributed
Many workstations can talk to the same IOC and devices
Scales well
As one CPU gets overloaded or IOC gets full, add another.
Share development with other beamline groups
Good tools for creating operator interfaces (MEDM) with no programming
Time-critical code (e.g. feedback) can run in IOC
Can run many applications (IDL, SPEC, SMART, Visual Basic) to talk to IOCs.
Choose the best application for the task
Can get quick-start using synApps
Disadvantages
Relatively complex