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Interfacing EPICS IOCs With Allen Bradley PLCs

Interfacing EPICS IOCs With Allen Bradley PLCs. Applications Recent enhancements Backwards compatibility Reliability. EPICS device and driver support for Allen Bradley DF1 protocol. Originally written for (and funded by) the KECK observatory

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Interfacing EPICS IOCs With Allen Bradley PLCs

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  1. Interfacing EPICS IOCs With Allen Bradley PLCs • Applications • Recent enhancements • Backwards compatibility • Reliability

  2. EPICS device and driver support for Allen Bradley DF1 protocol • Originally written for (and funded by) the KECK observatory • Recently updated for APT high power RF and personnel safety subsystems

  3. DF1 Driver Applications • IOC host architecture neutral • runs on PC, VME, and VXI IOCs • Point to point serial communication • Allen Bradley Data Highway communication • Allen Bradley KF2 standalone • Data Link DL PC low cost ISA card

  4. Recent Enhancements • Support for Allan Bradley PLC5 architecture • Output tracking • DF1 server • Others

  5. Support for Allan Bradley PLC5 architecture • PLC5 addressing • Thanks to Eric Bjorklund for improved ASCII address parser • PLC5 protocol • Data type safe R/W • Elements in files • Improved access control granularity

  6. Output Tracking • IOC initialization does not block for Initial output value query completion • Output records in invalid / undefined alarm state until this query completes • Output records track changes occurring in PLC (they are processed) • Potential side effects when output records have forward links

  7. DF1 server • Allan Bradley PLCs see EPICS records as elements in files in a PLC5 on DH+ • Reduced latency • Occurs when record addresses data highway node number of IOC

  8. Other Enhancements • Specification of independent scan rate for each PLC5 file • Each serial link or Data Highway may be assigned a different local node address • “drvSerial” does not delete tasks when a link drops out

  9. Backward compatibility • Continue to support original addressing and protocol of older PLCs • additional testing required for this version • Driver no-longer aborts a write in the queue so that it can be combined with another subsequent write

  10. Reliability • This driver has been supporting the APT high level RF and window test systems since the beginning of the calendar year • The driver has been very reliable on this very lightly loaded PLC5 system • Now have operational experience with Allen Bradley Data Highway

  11. Getting a copy of the DF1 protocol driver described here • KECK (Allan Honey) is the distribution point but I have not yet sent them a copy of this version

  12. In Memory Communication with VME Resident Allen Bradley PLC5? • Contact Eric Bjorklund (LANL LANSCE-6) for his driver • Both the DF1 driver (described here) and Eric’s VME driver use the same common PLC5 enhanced device support

  13. Conclusions • The Allen Bradley DF1 device / driver support has been upgraded to support PLC5s, output tracking, and DF1 server operation. • It has been very reliable under continuous production, but lightly loaded, operation of the APT high power RF system.

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