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Linux EPICS Industry Pack & Stepper Motor Support Report

Overview of Linux support for EPICS industry packs & stepper motors, including current progress, challenges, and future development. Discusses real-time operating system alternatives and initial goals for industry pack support on Linux platforms.

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Linux EPICS Industry Pack & Stepper Motor Support Report

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  1. August 2002 Marty Kraimer Linux EPICS IOC SupportIndustry Pack and Stepper MotorStatus ReportEPICS Meeting at IHEP

  2. 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.

  3. VISION • LINUX REPLACES VXWORKS • BUT: Linux isn’t a real time operating system • Non-pre-emptive kernel => 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

  4. 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.

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

  6. 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

  7. 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

  8. 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)

  9. 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

  10. 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 Franksen’s 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!!!

  11. 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.

  12. 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

  13. 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

  14. 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 Tim’s 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

  15. 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? • PC*MIP looks dead • PCI based Transient Recorder? • ???

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