Interfacing EPICS IOCs Interfacing EPICS IOCs With Allen Bradley PLCsWith Allen Bradley PLCs

• ApplicationsApplications

• Recent enhancementsRecent enhancements

• Backwards compatibilityBackwards compatibility

• ReliabilityReliability

EPICS device and driver EPICS device and driver support for Allen Bradley support for Allen Bradley DF1 protocolDF1 protocol

• Originally written for (and funded Originally written for (and funded by) the KECK observatoryby) the KECK observatory

• Recently updated for APT high Recently updated for APT high power RF and personnel safety power RF and personnel safety subsystemssubsystems

DF1 Driver ApplicationsDF1 Driver Applications

• IOC host architecture neutralIOC host architecture neutral– runs on PC, VME, and VXI IOCsruns on PC, VME, and VXI IOCs

• Point to point serial communicationPoint to point serial communication

• Allen Bradley Data Highway Allen Bradley Data Highway communicationcommunication– Allen Bradley KF2 standaloneAllen Bradley KF2 standalone

– Data Link DL PC low cost ISA cardData Link DL PC low cost ISA card

Recent EnhancementsRecent Enhancements

• Support for Allan Bradley PLC5 Support for Allan Bradley PLC5 architecture architecture

• Output trackingOutput tracking

• DF1 serverDF1 server

• OthersOthers

Support for Allan Bradley Support for Allan Bradley PLC5 architecturePLC5 architecture

• PLC5 addressingPLC5 addressing– Thanks to Eric Bjorklund for improved Thanks to Eric Bjorklund for improved

ASCII address parserASCII address parser

• PLC5 protocolPLC5 protocol– Data type safe R/WData type safe R/W

– Elements in filesElements in files• Improved access control granularityImproved access control granularity

Output TrackingOutput Tracking

• IOC initialization does IOC initialization does notnot block for Initial block for Initial output value query completionoutput value query completion– Output records in invalid / undefined alarm Output records in invalid / undefined alarm

state until this query completesstate until this query completes

• Output records track changes occurring Output records track changes occurring in PLC (they are processed)in PLC (they are processed)– Potential side effects when output records Potential side effects when output records

have forward linkshave forward links

DF1 serverDF1 server

• Allan Bradley PLCs see EPICS Allan Bradley PLCs see EPICS records as elements in files in a records as elements in files in a PLC5 on DH+PLC5 on DH+

• Reduced latencyReduced latency

• Occurs when record addresses data Occurs when record addresses data highway node number of IOChighway node number of IOC

Other EnhancementsOther Enhancements

• Specification of independent scan Specification of independent scan rate for each PLC5 filerate for each PLC5 file

• Each serial link or Data Highway may Each serial link or Data Highway may be assigned a different local node be assigned a different local node addressaddress

• ““drvSerial” does not delete tasks drvSerial” does not delete tasks when a link drops outwhen a link drops out

Backward compatibilityBackward compatibility

• Continue to support original addressing Continue to support original addressing and protocol of older PLCsand protocol of older PLCs– additional testing required for this versionadditional testing required for this version

• Driver no-longer aborts a write in the Driver no-longer aborts a write in the queue so that it can be combined with queue so that it can be combined with another subsequent writeanother subsequent write

ReliabilityReliability

• This driver has been supporting the APT This driver has been supporting the APT high level RF and window test systems high level RF and window test systems since the beginning of the calendar yearsince the beginning of the calendar year

• The driver has been very reliable on this The driver has been very reliable on this very lightly loaded PLC5 systemvery lightly loaded PLC5 system

• Now have operational experience with Now have operational experience with Allen Bradley Data HighwayAllen Bradley Data Highway

Getting a copy of the DF1 Getting a copy of the DF1 protocol driver described protocol driver described herehere

• KECK (Allan Honey) is the KECK (Allan Honey) is the distribution point but I have not yet distribution point but I have not yet sent them a copy of this versionsent them a copy of this version

In Memory In Memory Communication with VME Communication with VME Resident Allen Bradley Resident Allen Bradley PLC5?PLC5?• Contact Eric Bjorklund (LANL Contact Eric Bjorklund (LANL

LANSCE-6) for his driverLANSCE-6) for his driver

• Both the DF1 driver (described Both the DF1 driver (described here) and Eric’s VME driver use the here) and Eric’s VME driver use the same common PLC5 enhanced same common PLC5 enhanced device supportdevice support

ConclusionsConclusions

• The Allen Bradley DF1 device / driver The Allen Bradley DF1 device / driver support has been upgraded to support support has been upgraded to support PLC5s, output tracking, and DF1 server PLC5s, output tracking, and DF1 server operation.operation.

• It has been very reliable under It has been very reliable under continuous production, but lightly continuous production, but lightly loaded, operation of the APT high loaded, operation of the APT high power RF system.power RF system.