1. Programming Logic Controllers Selection, Components, & Communication - Chapter 2

2. PLC Process control computers no number crunching no graphics Event driven industrial control systems Environmentally hardened Dust, temp, noise (em) Easy Repair, operate, and program

3. PLC Selection Mfg support Serviceability Flexibility Expandability Programming software Training Documentation

4. Allen-Bradley SLC 500 Fixed Single housing for power supply, cpu, I/O modules Modular

5. Allen-Bradley SLC 500 Components Chassis Rack / backplane for PLC and modules Distributes power slotted Power Supply – sufficient for all components Processor – chosen for memory and math I/O Modules Digital I/O modules Analog I/O modules Specialty Distributed / networking I/O modules

6. Addressing Slot 0 next to power supply CPU Slot 1+ hold other modules I:1(input module in slot 1) O:2 (output module in slot 2) I:3, O:4, I:5, O:5 May have many modules Each module has several ports/terminals I:1/2input on module 1, terminal 2 O:2/1 output on module 1, terminal 1 A Fixed PLC may have both Input and output in slot 0 I:0/0 O:0/0

7. Sourcing and Sinking Sourcing and Sinking refer to electrical current flow Sourcing modules connect to sinking modules and vice versa Sourcing occurs when current flows out of PLC circuit Sinking occurs when current flow into PLC port

8. PLC Memory Expansion and Usage System memory (25%) User Memory (75%) User Memory Ladder logic program(s) System Memory Input status Output status Timers’ status Counters’ status Math and logic instruction status

9. Communications Channel 1 and Channel 0 occasionally Channel 0 for peripheral devices Bar code scanner Printer Channel 1 Communication with other plc/pcs RS232 interface for programming Ethernet or other network communications

10. Communications Baud Rate Parity DTE (initiate) and DCE (respond) Simplex, Half Duplex, Full Duplex

11. Programming Modules Hand held Common for small devices Dedicated Part of the PLC circuit/station Computer Need a device to translate States/setting Off/program/disabled/run/forced