CLS Machine Protection and PLC Hardware Presentation to Beamlines Group Elder Matias Canadian Light Source University of Saskatchewan October 20, 2001

What is a PLC? PLC hardware has evolved out of electrical engineering as a “soft” method of implementing relay logic. Today, modern PLC technology uses conventional processor technology tailored for real-time process control applications Key features include: –Integrated IO support –Integrated Networking support –Integrated Programming Tools –Remote Diagnostics –High MTBF, e.g., 10 year MTBF on the Processor Module and 30 year MTBF on the Siemens S7 hardware

How Does PLC Software Work? PLCs use a Get, Process, Set model based on sampling IO, however most PLC systems also have support for interrupts PLC programming is normally interpreted by a virtual machine Wait Get Process Set

How Are PLCs Programmed? In the old days, they were programmed using Relay Logic Today most PLC programming is done using IEC programming languages: –Function Blocks (graphical language) –Structured Text (Pascal like language) –Instruction List (Assembler like language) –Ladder Logic (relay logic graphical language) C, C++, FORTRAN, etc. can also be used

MODICON Momentum Low End PLC, based on a 386 processor TCP/IP based PLC system PLC runs a web server At CLS these are used extensively for vacuum protection, conventional process control (heat exchangers) and assorted slow changing signals.

S7 Siemens S7/300 and S7/400 is used for mid to high end applications Profibus network Based on a large family of industrial control, factory automation and vision modules The S7/400F is certified by the TÜV for use in safety critical applications CLS uses the S7 for RF control on the booster, storage ring, and cryogenics The S7/400F is used for personnel safety applications

Machine Protection Design Principles Accomplished using mostly redundant hardware Either two PLC systems or a PLC and dedicated hardware For Vacuum control “smart” Pressure Transducer Hardware with programmed trip points are used for redundancy with a PLC

Operator Interface Based on an “Operating Envelope” around acceptable states of the machine Machine Protection algorithms provides a permissive to allow certain operator actions The Operator Interface Software can not override the protection functionality