ether ip epics ethernet ip support for controllogix
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ether_ip - EPICS EtherNet/IP support for ControlLogix

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ether_ip - EPICS EtherNet/IP support for ControlLogix. Kay-Uwe Kasemir, LANL Nov. 2000. EtherNet/IP. IP = Industrial Protocol Evolved from “ControlNet over EtherNet” SIG Encapsulates CIP in TCP & UDP (Ctrl. & Info. Protocol, shared by DeviceNet and ControlNet) Part of ControlNet Specs:

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ethernet ip
EtherNet/IP
  • IP = Industrial Protocol
  • Evolved from “ControlNet over EtherNet” SIG
  • Encapsulates CIP in TCP & UDP
    • (Ctrl. & Info. Protocol, shared by DeviceNet and ControlNet)
  • Part of ControlNet Specs:
    • Open DeviceNet Vendor Assoc.,http://www.odva.org
ethernet ip spec details
EtherNet/IP Spec. Details
  • ControlNet Spec.2 Errata 1, E.Net. still in red
  • Open portion of CIP (object & service codes):
    • How to route messages
    • How to read serial number and vendor code
  • Vendor specific:
    • Get data of real interest, e.g. PLC values
  • This driver:CIP Read/WriteData as used byAllen Bradley ControlLogix PLCs
    • Round-trip request/response mechanism
    • Subscription (ForwardOpen) with triggered updates via UDP not implemented/documented by AllenBradley
epics driver device
EPICS Driver/Device
  • No special hardware, neither for setup nor runtime
  • IOCs (pc486, PPC), command-line (Win32, Unix)
  • Can read & write any tag on PLC
    • DTYP=“EtherIP”, INP=“@plc1 PS1RB2”
    • also: INP=“@plc2 arraytag[21]”, “@plc2 struct.elem”
    • REAL, INT, DINT, BOOL,scalars, struct. elements, arrays
    • no need to “publish” tag in PLC’s LadderLogic or program ControlNet connection to allocate bandwidth
    • Records: ai, ao, bi, bo, mbbi, mbbo, mbbiDirect, mbboDirect
  • INP/OUT can be changed at runtime to use different tag on different PLC!
  • Handles disconnects/reconnects (e.g. PLC reboot)
driver device details
Driver/Device Details
  • One communication thread per PLC
  • Combines requests to minimize transfers
    • (up to ~500 byte PLC buffer limit)
  • Arrays are transferred as a whole (default)
  • Output records:
    • Monitors PLC, updates rec. on change
  • Supports SCAN=I/O Event (also for e.g. 30Hz scans)
  • Provides statistics: min/max/last scan times, #errors, ...
  • Performance: about 8ms per transfer
      • Single REAL tag: 8ms
      • BOOL[352]: 8ms
      • 3xREAL[30]: ~20ms (combined requests)
conclusion
Conclusion
  • Setup:
    • No additional hardware (neither for PC, IOC, nor communication setup)
  • Use:
    • No special LadderLogic required, though arrays might be preferred (performance)
    • Good IOC support (I/O Event, runtime change)
  • Performance:
    • 8ms/transfer, susceptible to network delays
    • good enough for most applications?
slide7
Taken after about 46000 runs,

PPC IOC, 350 BI @10Hz, 150 AI @ 1Hz, switched network.

After 1 week: max. scan time 0.15 sec

Test
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