PLC Selection Criteria and Results

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PLC Selection Criteria and Results
David Dudley Sep 8, 2009
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Outline

• What are the PLCs used for.
• Which PLCs were on the short list, and why.
• Requirements for PLC integration.
• What tests were performed.
• Evaluation.
• Results.

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What are the PLCs used for

• Complete control of accelerator operations
• Automatically manages control of machine
  operations under steady state conditions.
• Controls access to accelerator facilities.
• Provides the Personnel Protection System (PPS)
  which should prevent exposure to dangerous areas
  of facility.
• Manages the Equipment Protection System (EPS) to
  prevent damage to equipment during operation.
• Most actual control interfaces are linked through
  the PLC I/O systems.

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What are the PLCs used for (contd)

• Slow and Moderate Speed I/O are linked through
  the PLC, which can acquire and time stamp data.
• Automatic/semi-automatic or manual control of
  various subsystems used in the accelerator.
  These systems include
• Control and automatic operations of the Vacuum,
  RF, Power Supply, and other subsystems.
• Almost all equipment monitoring.
• Conventional Systems automatic control and
  monitoring.
• HVAC monitoring.

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What are the PLCs used for (contd)

• Provides secure, automatic shutdown in case of
  personnel intrusion into secure areas.
• Protects the user from himself.
• Prevents access to hazardous areas during
  operation.
• Monitors radiation hazards in occupied areas.
  Should dangerous levels occur, takes protective
  action.
• Provides for sequential systematic searching of
  secured areas before machine operation possible.
• Enables machine to operate when all required
  areas are secured, and all interlocks satisfied.

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Which PLCs were on the short list, and why

• Rockwell Automation (Allen Bradley) Control Logic
  and Compact Logic.
• Handles Safety and Normal control systems
• Fast, Compact Logix performs 1k boolean
  instructions in 0.08 ms, Control Logix (L63) in
  0.04 ms. Typical instructions in 0.5ms/1k,
  0.25ms/1k respectively.
• Very popular in the US.
• Full complement of functions.
• Capable of loading/storing XML program
  descriptions.
• Used by a great variety of customers

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Which PLCs were on the short list, and why

• Siemens S7-300 and S7-400.
• Used in a variety of control applications,
  including many accelerators.
• Very popular in Europe.
• Handles Safety and Normal control systems.
• Limited text import/export capabilities.
• Full complement of functions.
• Fast, S7-315 performs 1k Booleans in 0.1ms,
  S7-317 performs in 0.05 ms, Typical
  instructions in 2 ms/1k, 0.2 ms / 1k
  respectively.

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Which PLCs were on the short list, and why

• Yokogawa FA-M3
• Extremely fast. 533 Mhz Powerpc.
• Very popular in Japan.
• Operates as a Ladder Logic CPU (Sequence mode),
  or as an embedded Linux IOC.
• IOC Support was developed at KEK.
• Very fast, F3SP67-6S performs 1k boolean
  operations in 0.0175 ms, Typical instructions
  in 0.07 ms / 1k.
• Handles standard EPICS record definition files.

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Which PLCs were on the short list, and why

• GE Fanuc PACSystems RS7i.
• VME64 Based. Up to a 1.8Ghz Pentium-M processor.
• VME Crate chassis size would make easy
  integration.
• Use worldwide in petrochemical, manufacturing,
  electrical, and pharmaceutical industry
• Fast. Booleans 0.02ms/1k, Typical 0.03ms/1k.
• All systems supported by single software package.
• Software supports text input/output (degree not
  known).

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Requirements for PLC Integration

• All IO is to be defined through the IRMIS system.
• PLC programming software MUST be able to load and
  store files created through the IRMIS system that
  defines I/O and or logic.
• PLC programming must be available over ethernet.
• All IOC communications to the PLCs will take
  place over ethernet.

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What tests were performed

• Simple interface tests to evaluate capability of
  PLC to integrate with EPICS.
• Rockwell (A-B) EPICS response is slow, but it
  seems the limitations are inherent to the driver.
  Data size does not seem to affect transfer rate.
• Siemens interface is data structure based, and
  requires PLC programming to build data block and
  send to host.
• Yokogawa interface is register based, and
  requires a knowledge of which register number
  contains data required.
• GE interface is Modbus based, and has same
  limitations as the Yokogawa interface.

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What tests were performed

• Data capture tests that evaluated
  acquiring/storing/timestamping 12 analog values.
• Acquired data on timed basis, with one sample
  each 10 ms (limitation of the Siemens module
  used). A-B and Yokogawa were capable of
  performing much faster, with the A-B performing
  at one sample each 5 ms, and consuming 70-90
  usec./cycle. Faster hardware is available as
  well.
• Yokogawa IOC module had no problem acquiring data
  as fast as the scan times available would allow
  (0.05 sec, I believe). After additional
  research, the Yokogawa times could be much
  faster, given the speed of the hardware.

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What tests were performed

• No GE Hardware was tested.
• No hardware was available, although research
  seems to point to the capability of very high
  performance from the system.
• It was decided not to pursue testing with the GE
  equipment, due to equipment cost and other
  constraints.

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What tests were performed. Additional logic for
evaluation

• Basic logic for First Optical Enclosure PPS
  Interlocks.
• FOE-Permissive TRUE when FOE is secured
• Beamline Switch Permissive TRUE when Beamline
  switch is in the READY position.
• Rad Monitor Permissive TRUE when Radiation
  within safe limits.
• Safety Shutter Closed Permissive TRUE when
  Photon Safety Shutter is closed and secured.

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Siemens Ladder Logic Example

• Siemens ladder logic editor equivalent of the
  logic becomes the following form

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Siemens Ladder Logic Example

• Exporting the ladder into a text file produces
  the following

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Siemens Import Example

• Loading the text file into the ladder editor
  provides the following output

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Limitations on Siemens Import Example

• Problems with the Siemens import/export file
• All symbolic information has been removed
• All comment information has been removed
• I/O references are to absolute locations
• No tagname information has been included
• Additional Text File information
• There is a text format file, which allows
  import/export of system configuration. The file
  allows complete definition of programs, and
  includes symbols and tags. The file format is
  unique, as far as I can determine, has no
  standard definition, and cannot be merged into
  existing logic.

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Allen Bradley Ladder Logic Example

• The ladder logic editor in Allen Bradley uses the
  same format, with the following exceptions
• Symbols are defined in the one of the Tagname
  tables (either Controller or Program local), and
  must be defined before they can be used.
• Outputs are allowed inline with logic, and allow
  logic to continue around them.

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Allen Bradley Logic example
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AB XML File Example
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Allen Bradley Text file import/export

• Text file format is XML.
• File format is documented (and supported) by AB.
• Sample file text is included, but not shown
  completely.
• File includes all information on controller, I/O
  configuration, Tagnames, and program file
  definitions.
• Loading XML file will exactly reproduce the
  binary image from previous save.
• Format definitions will allow a programmatic
  creation of complete program image. Import also
  allows partial file imports.

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Yokogawa FA-M3

• Processor is comparable to the VME cards
  currently being used.
• Module executes Linux out of a removable compact
  flash card.
• KEK has ported the Linux IOC to the device. A
  driver has been written that allows direct
  control and communications with both the I/O
  hardware installed in the chassis, or a companion
  CPU that can run either Linux or sequential
  ladder logic.
• Up to 4 processor modules can be installed.

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Yokogawa FA-M3 (contd)

• Sequence CPU
• Logic program software is called WideField2.
• Software cannot load or store any type of
  non-binary file describing logic operations.
• Software I/O cannot be defined externally, and
  all logic and I/O must be defined in the
  software.
• Software does allow a cross reference file
  containing tagnames (symbols) and I/O address
  information.
• EPICS driver is available (netdev), however was
  not evaluated as I did not have access to the
  sequence CPU programming software.

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Yokogawa FA-M3

• Linux CPU
• IOC interfaces with I/O using Linux kernel module
  driver, which is closed source.
• Hardware performance is outstanding, and far
  exceeds any of the other systems evaluated.
• Hardware support includes 64 channel digital
  input and output modules, but analog modules are
  limited to 8 channels maximum.
• Can directly communicate with sequence CPU
  installed in same chassis.
• Not the desired target for reliability/flexibility
  .

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GE Fanuc PacSystems RS7i

• Based on VME64 Chassis. Chassis sizes vary from
  10 slots to 18 slots, with both front and rear
  I/O access.
• Supports both standard and redundant
  configurations.
• Memory capacities from 10 Mb to 64Mb on processor
  card.
• Capable of using high density I/O cards.
• Digital inputs and outputs capable of 64 channels
  on a card.
• Analog inputs capable of 64 channels on a card,
  16 bit accuracy.

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GE Fanuc PacSystems RS7i

• I/O performance is well within requirements,
  exceeding the required performance for the Time
  stamped I/O, and providing much better analog
  performance in general.
• Does not meet or exceed capabilities of the
  Yokogawa FA-M3, but exceeds capabilities of other
  PLCs in comparison.

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PLC Selection Advantages/Disadvantages

• Allen Bradley and GE are US Companies, and
  qualify for the US company incentives.
• Siemens has been used successfully in a number of
  accelerators, including NSLS.
• Yokogawa is being successfully used by KEK.
• GE is known for reliability and capability
  worldwide.
• Yokogawa can be a self-contained IOC.
• AB, Siemens, and GE will all require IOCs to
  communicate with EPICS.

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PLC Selection Advantages/Disadvantages

• AB directly supports complete text file
  configuration and programming.
• It is XML standard, documented, and considered a
  standard program storage format.
• Siemens supports text I/O and logic
  configuration.
• Text file is custom format, and apparently not
  documented.
• GE states they have text file capability, but
  have not seen it operate.
• Yokogawa Sequence (LADDER) PLCs support I/O
  configuration through text files, but cannot
  accept logic using text formatted files.

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PLC Selection Advantages/Disadvantages

• Yokogawa Linux IOC supports direct control of
  hardware, or direct communications to Yokogawa
  Sequence PLC in same chassis.
• Yokogawa runs IOC under Linux (advantage).
• Yokogawa runs IOC under Linux (disadvantage).
• All PLC units support I/O updates on polled or
  interrupt basis.
• All PLC units (except Yokogawa IOC) must be
  polled by IOC in order to retrieve data.

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Sample Configurations

• First requirements set is based on information
  from Russ OBrian and the Conventional Facilities
  group.
• Second requirement set is based on information
  provided by Bob and Huijuan Vacuum control and
  monitoring systems.
• Requirements were developed to provide unbiased
  design requirements for comparative analysis.
  These requirements take into account only the
  required I/O for a particular application, and
  not the advantages of any particular product.

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Sample Configurations (contd)

• Conventional Facilities sample.
• Based on requirements for LINAC/Booster Cooling
  Skid, as per Russ OBrian (6/18/09 design).
• Requirements include
• CPU w/ gt512k ladder logic memory.
• Ethernet port.
• 16 Digital Inputs.
• 16 Digital Outputs.
• 4 Analog Inputs (16 bit resolution).
• 5 Analog RTD inputs (16 bit resolution).

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Sample Configurations (contd)

• Single PLC/Cell Storage Ring vacuum
  configuration.
• As per Bob / Huijuan.
• CPU with gt1.5 Mb Ladder program space.
• Ethernet Communications port.
• 6 High Speed Analog Inputs with Timestamping
  capability.
• 10 High Speed Digital Inputs with Timestamping
  capability.
• 18 Analog Inputs.
• 178 Digital Inputs.
• 64 Digital Outputs.
• All Analog inputs to be 16 bit accuracy.

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Sample Configurations (contd)

• Requests were sent to each vendor, to supply
  priced quotation for a system that met the
  requirement.
• All documentation on each system to be available
  through internet, or supplied with quote from
  vendor.
• In addition, due to high I/O count possibilities,
  both Yokogawa and GE were requested to provide
  quotes for a single system capable of providing
  control/monitoring for a complete cell. This
  included the Storage Ring, 2 Insertion Devices,
  and 2 Beamlines.

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PLC Comparison Matrix
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PLC Capabilities Comparison Chart
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Results
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Recommendation

• 1. Limit selection to one, or two vendors.
• 2. Preferred selection is Rockwell (A-B)
  hardware.
• All levels of hardware are supported under
  Ethernet/IP and CIP, and allow direct access by
  tagname.
• 3. Alternate selection is Siemens S7-300 family.
• S7-200 cannot communicate with EPICS, and is
  unusable for anything requiring access to EPICS
  without substantial additional configuration and
  hardware/software.
• S7-200 programming software has additional
  limitations limiting functionality.
• Yokogawa has no SIL rating, and must be
  disqualified.