Hall Cs HMS PLC Controls by Steven Lassiter

Hall C’s HMS PLC Controls by Steven Lassiter

What Constituents a PLC System • • PLC (processors) Programming. I/O modules. Field Device Signals (sometimes signal conditioners are needed). Communication/Interfacing to other systems. Wiring and associated hardware (Racks, local controls). Human to Machine Interfaces, HMI. Databases and security.

What is a PLC? • Programmable Logic controller : miniature industrial grade computers consisting of hardware and software used to perform control functions. • The first PLC was developed in Bedford Ma. in 1968 and was called a Modular Digital Controller (MODICON) and was used by GM to replace mechanical relays. • The CPU reads input data from field devices via input modules, executes a control program and writes output.

PLC Programming • Programming can be done by a combination of computer languages: ladder logic, function blocks, flow diagrams, Basic and even C to name a few. • Programming is sequential for the most part. • Certain tasks(programs) can be given higher priority (scan rate).

Ladder Logic Program

Function Block Program One PID Function block can have over 160 parameters in it.

Program compiler Many Subprograms (Tasks)

Inputs /Outputs • Inputs can be analog (voltage or current) or discrete voltage signals (1 or 0). • PLC uses input/output modules to handle signals from field devices. • Can also use higher level communication devices: RS 232, Ethernet, etc. • Many third party devices can talk to the PLC.

PLC Redundant Chassis Layout Seven Module Chassis Communication Module Remote Chassis Blank Slots Communicator PLC PSU Redundancy Module

Typical I/O Chassis Layout Ten Module Chassis PSU Communication Module to PLC

Field Devices • Temperature Sensors • Magnetic field measurements • Pressure gauges • Vacuum gauges • Cryogenic Liquid Level Meters • RS 232/ RS 434, etc • Relays • • Voltage Taps Current measurements Strain gauges Motor drivers (DC & AC) • LVDT & position indicators • Flow Measurements • Encoders

Communication • • Information can be passed to the PLC through: Backplane Controlnet Devicenet Ethernet Uses OPC (OLE for Process Control) OLE = Object Linking & Embedding.

Control. Net is one way that the PLC talks to remote I/O. RG 6 cable terminated on each end. Remote I/O can be located up to several Kms away.

Cabling and Racks • PLC Rack • Local Control Rack / Signal Conditioning

Human to Machine Interface (HMI) RSVIEW & RS-Studio

Conclusion • Truly Redundant systems: Dual PLCs, I/Os, communication devices. • Hot Swap of I/O devices and PLC (when redundant PLCs are in use). • Ease of programming, auto tag name generator and predefined logic code, drag and drop programming. • Reliability is very good, especially in harsh environments, although intense radiation is always a problem. • Service and monitoring by engineers from home base, reduces downtime (wait-time). Web Based HMIs. • Security of critical sensitive areas. Users may only have restricted, well defined access to magnets. • Trending, maintaining of databases and keyboard entry logging are readily available. • Capability to read/write to EPIC variables exists.

Hall D’s Solenoid

Hall D