Linux EPICS IOC Support Industry Pack and Stepper Motor Status Report EPICS Meeting at IHEP

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Linux EPICS IOC SupportIndustry Pack and Stepper
MotorStatus ReportEPICS Meeting at IHEP

• August 2002
• Marty Kraimer

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Overview

• First presented at EPICS meeting at BESSY in May
  2002
• Describes work in progress to support Linux PC
  IOCs
• First Target Applications
• Synchrotron Beam line Applications
• Working with Tim Mooney's group at APS
• Some APS/ASD (Accelerator) Applications
• Example Monitoring Conventional Facility data
• First Hardware Support
• OMS PCI Motor support (Joe Sullivan from Tim
  Mooney's group)
• PCI Industry Pack Carrier
• Serial, gpib, adc, dac, digital I/O.

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VISION

• LINUX REPLACES VXWORKS
• BUT Linux isnt a real time operating system
• Non-pre-emptive kernel gt no context switch while
  kernel active.
• Interrupts can be disabled for long periods of
  time.
• Worst case can be 100s milliseconds. (2.4 Kernel)
• Future
• Development kernel is pre-emptive.
• Work in progress so that interrupts disabled for
  short times.
• Other possibilities
• RTLinux
• RTAI
• RTEMS

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Modified VISION

• Existing Linux good enough for some Applications.
• 2.6 Kernel will be good enough for more
  Applications.
• If small part of Application needs strict real
  time.
• Use RTLinux/RTAI.
• For demanding Apps use RTEMS or stay with
  vxWorks.
• RTEMS
• Open Source
• Tests show real time performance equivalent to
  vxWorks
• Not as complete an environment as vxWorks
• Well supported by R3.14
• Eric Norum and Till Straumann are very interested
  in it.
• See EPICS 3.14 home page and Till's talk at BESSY
  EPICS meeting.

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Initial Goals

• Industry Pack Support on Linux IOCs
• Standard PC platforms original goal
• In the future
• CompactPCI
• Other platforms, eg. VME
• Work with Tim Mooneys group (synApps)
• Joe Sullivan working on PCI based motor support.
• IP Motor gt usable for some beam line
  applications.
• Expect there will be a lot of interest.
• Requires Message Passing Facility (MPF)
• When IPMotor support ready some synApps can be
  done.

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Industry Pack Support

• Industry Pack Small Low Cost I/O Modules
• PCI40A IP Carrier SBS GreenSpring Modular I/O
• PCI bus card that holds four IP modules
• Fits in standard PCI slot.
• MPF and synApps supports following IP modules
• SBS IP Octal Serial eight serial ports
• SBS IP488 GPIB interface
• SBS Ip-uniDig family of Digital I/O modules
• Acromag IP330 ADC 16 bit 16 channel DI or 32
  channel SE
• Systran DAC128 DAC 8 channel 12 bit DAC
• Goal is to support all of this on Linux

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Progress

• Linux Kernel support now exists for
• Generic IP carrier support (Like ANJs IPAC
  support)
• PCI-40A SBS Quad IP Carrier for PCI Bus
• IP-488 (Green Springs GPIB IP using the ti9914)
• IP-Serial (Green Springs IP-Octal)
• Simple driver for OMS PCI Motor driver (Proof of
  Concept only)
• Message Passing Facility (MPF) ported to 3.14
• Lots of cleanup.
• Ran several tests successfully
• Still at preAlpha stage
• Gpib and Serial still very buggy!!
• No Documentation

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Implementation Strategy

• Clear Separation between Linux and EPICS
• Linux drivers have NO knowledge of EPICS
• Separate development area. Separate releases.
• Usable by non-EPICS and non-MPF users
• Linux char drivers (ioctl calls heavily used)
• Drivers written with real time performance goal
• Allow complete transaction with single user level
  call
• Read, write, writeRead typical request
• Allow easy addition of code called by interrupt
  handlers
• For now testing with ordinary user level process
• Later will test using real time scheduling
• Will try multi-priority iocCore (existing 3.14
  does not do this)

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PCI40A Support

• Generic IP Carrier Support
• Similar to what Andrew Johnson did for drvIpac
• The PCI40A driver registers with the generic
  interface
• Additional carrier drivers can be added
• Individual IP module drivers interface via
  generic support
• cat /proc/industryPack
• Reports all industry pack modules
• PCI40A driver registers with the generic
  interface
• IP module drivers call the generic interface

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Some Details aboutGPIB support

• SBS (GreenSpring) IP-488 Industry Pack module.
• Linux kernel driver
• Interfaces to generic IP carrier
• gpibLinux.h describes user level interface (Linux
  ioctl calls)
• requestRead, requestWrite, requestWriteRead,
  requestCmd
• Each is single kernel call.
• EPICS code
• Implements Benjamin Franksens interface
• Usable by for any GPIB device support that uses
  Benjamin's code
• For Test the DG535 support code was ported to
  3.14
• Easy port
• Works for awhile on Linux before crashing!!!

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Some Details aboutSerial Support

• Linux kernel driver
• serialLinux.h describes user interface.
• Uses Linux ioctl calls.
• requestRead, requestWrite, requestWriteRead
• requestConfig baud rate, stop bits, etc.
• requestSniff report all I/O for requested amount
  of time
• requestSetInputHandler
• Defines Input Handler interface
• Interrupt code calls registered handler for each
  input character
• Standard input Handler provided
• Easy to add additional handlers.
• Some testing but not complete. Not yet interfaced
  to MPF.
• Will also support the Linux tty interface.

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Still to do

• IP330 (ADC) Nothing implemented now.
• Existing IP330 allows floating point in interrupt
  handler
• Not allowed in Linux Kernel
• DAC128V (DAC) Nothing implemented now
• ipUnidig (Digital I/O) Nothing implemented now
• OMS Motor support
• Have sent/received commands from OMS PCI Motor
  driver
• Joe Sullivan from Tim Mooney's group is working
  on support

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Immediate Plans

• Make the GPIB and serial drivers more reliable
• GPIB
• Find and fix bugs
• Serial
• Implement Linux tty interface
• Find and fix bugs
• Document IP carrier, gpib, and serial drivers
• Create alpha release under the EPICS open source
  license

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After Alpha Release

• Interface serial support to MPF
• Implement support for digital, and analog i/o
• Linux Drivers
• Interface to MPF, i.e. to EPICS
• Work with Tims group to support synApps on Linux
• Look for APS/ASD applications.
• Many many records use IP serial support.
• Many use IP330 support.
• Monitoring only and not time critical
• Work on real time performance
• IOC Spawn a real time process and use
  multipriority posix threads
• When available use 2.6 Linux Kernel

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Possible Future Tasks

• Allow user level to access IP register space?
• Is this a good way to go?
• Is this better than kernel drivers?
• What about interrupts?
• Successor to IP?
• PMC?
• PCMIP looks dead
• PCI based Transient Recorder?
• ???