EPICS Developments at the Australian Synchrotron

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EPICS Developments at the Australian Synchrotron
DSP EPICS driver for the General Standards 16AIO
analog card EPICS driver for the Galil range of
motor controllers Author Mark Clift Presented
by Nicholas Hobbs
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1. Analog Acquisition

• Many Analog acquisition cards are used, the 16AIO
  from General Standards is the most commonly used
  on site
• 16AIO card linearity and noise characteristics
  are average for a 16 bit card
• 16AIO is faster than average (300K samples
  cumulative), allowing DSP methods to be applied
  within the EPICS driver
• The 16AIO is a mezzanine board and is available
  in many form factors, we use PCI at the
  Australian Synchrotron

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16AIO EPICS Driver

• The 16AIO EPICS Driver was created using the
  IP330 driver as initial basis
• It has an Asyn based structure and is compatible
  with the fast PID feedback software written by
  Mark Rivers
• 16AIO hardware includes a 32Kb sample buffer
  which allows rapid data acquisition
• At the driver layer, sample rates up to 30 KHz
  are used
• The maximum EPICS update rate is 1.5 KHz
• Achievable speed depends on computing hardware,
  operating system, and machine load.

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16AIO Updates to registered clients (eg. EPICS)

• The 16AIO driver functionality is based on
  regular updates to registered clients (eg. EPICS
  layer) via Interrupt I/O
• Fundamental frequency of updates to clients is
  specified by the LcaioSetup comand
• Update frequency of individual signals is
  specified by a combination of the fundamental
  update frequency and the LcaioAiSignalSetup
  command. The LcaioAiSignalSetup command simply
  divides the fundamental update frequency by an
  integer

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16AIO DSP methods

• Two very basic DSP methods are employed by the
  16AIO driver, they are
• Sample Averaging
• Effective number of bits (ENOB)
• The ENOB and averaging algorithms do not operate
  when only one sample is available per client
  update period, multiple samples are required
• The effective bit (ENOB) resolution of the
  resultant data is calculated from the following
• Fos 4w x fs
• Fos Sampling frequency used
• fs Original sampling frequency requirement
• W Extra bit(s) of resolution

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Uses of 16AIO at the Australian Synchrotron

• Fast feedback system on the Microspectroscopy
  beamline
• General analog inputs at the Imaging beamline
• Booster and Storage ring current measurement (see
  below, red line)

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2. Galil EPICS driver for motor control

• The Galil driver has a native EPICS driver/device
  layer, and does not use Asyn
• Galil driver interfaces with the motor record and
  a collection of standard EPICS records
• The standard records are used to provide
  control/monitor interfaces for features that the
  motor record does not support (e.g. gear ratio)
• The Galil driver is compatible with all motor
  controllers in the Galil range
• The Galil driver has an extensive list of
  parameters which can be difficult for first time
  users to comprehend

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Galil EPICS driver

• The Galil driver has many unique features
  including
• Ability to accept and work with user-written
  Galil code
• Ability to read two encoders at all times per
  motor. The encoder used in the motor record can
  be swapped at run time while the motor is stopped
• A generic interface is provided so new
  functionality can be added to the driver, whilst
  providing a full EPICS interface
• Allows master/slave relationships amongst motors
• Has closed loop stepper control that is
  compatible with master/slave relationships

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Galil EPICS driver

• Further features
• Stall detection of any active encoder that is
  related to a motor
• EGU travelled after limit activation can be
  specified, useful for tricky switches, or fast
  moving heavy loads

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Galil controllers in use at Australian Synchrotron
Location Motor count
Powder diffraction - End station 24
Powder diffraction - Diffractometer 4
X-ray Absorption - End station 24
SAXS/WAXS - End station 28
SAXS/WAXS - IVU 2
Infrared - End stations 17
Protein Crystallography - IVU 2
Microspectroscopy - End station 16
Microspectroscopy - IVU 2
Imaging beamline - Wiggler 2
Imaging beamline - End stations 36

Total 157














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Galil controller models that we use

• MC 8000
• Based on the 2183 Galil motor controller
• Eight axis, integrated parker drive system
• Beamline and End station motors
• Front Internal Rear

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Galil controller models that we use

• MC 4000/2000
• Based on the 2143/2123 Galil motor controller
• Four/two axis, external drive system
• Insertion devices, and heavy equipment (e.g.
  SAXS/WAXS table)
• IVU Control rack IVU

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Galil motor controllers, our impression

• Reliable, had no hardware failures
• Easy to use and quick to get going
• In comparison we have had many hardware failures
  in PC-104 Delta Tau controllers, particularly the
  communications board
• AS very satisfied with Galil support (e.g. They
  provided generic SSI encoder interface firmware)

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Thank you for your attention
Australian Synchrotronwww.synchrotron.vic.gov.au
www.synchrotron.org.au
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For more information and software

• DSP EPICS drivers for 16AIO analog card
• EPICS drivers for Galil motor controllers
• Mark Clift
• mark.clift_at_synchrotron.org.au
• ftp.synchrotron.org.au/pub/EPICS09