1. EPICS support for ControlLogix via EtherNet/IP Kay-Uwe Kasemir, LANL May 2001

2. PS PLC CNet Allen-Bradley ControlLogix SNS: HPRF, Vac., RCCS, Facility, … Up to 7MB, multithreaded, … Symbolic ‘tag’ names, no ‘I10:12’ Accepts DeviceNet, ControlNet, EtherNet/IP, … like any I/O module

3. IP = Industrial Protocol Evolved from “ControlNet over EtherNet” SIG Encapsulates CIP in TCP & UDP (Ctrl. & Info. Protocol, shared by DeviceNet and ControlNet) Specs. used to be part of ControlNet, now available as separate “EtherNet/IP”: Open DeviceNet Vendor Assoc., http://www.odva.org

4. EtherNet/IP Spec. Details 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 by Allen Bradley ControlLogix PLCs Round-trip request/response mechanism Subscription (ForwardOpen) with triggered updates via UDP not implemented/documented by AllenBradley

5. 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 Records: ai, ao, bi, bo, mbbi, mbbo, mbbiDirect, mbboDirect 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 INP/OUT can be changed at runtime to use different tag on different PLC! Handles disconnects/reconnects (e.g. PLC reboot)

6. 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: (default “System Overhead Time Slice”) Single REAL tag: 11ms (7ms with 50% SOTS) BOOL[352] + 3xREAL[30]: 15ms + 25ms (combined requests)

7. Transfer Time Histogram 352 BI @ 10Hz, 3 x REAL[40] @ 2 Hz

8. 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: 11ms/transfer, susceptible to network delays good enough for most applications?