MicroLogix Packaged Controllers Programmable Controller Basics Introduction

Traditional PLC Concept PLC performs relay equivalent functions PLC performs ON/OFF control Ladder diagram program representation Designed for industrial environment Designed for ease of use and maintenance

PLC Advantages Ease of programming Ease of maintenance Designed for industrial environment Quick installation Adaptable to change

Today's Higher Level Control Capability Arithmetic Data Comparison Word Manipulation Master Control Relay Instructions Program Skip Capability Sequencing Matrix Data Manipulation Proportional, Integral, Differential (PID) Control

Programmable Controller Inputs Outputs CRCR What Is A Programmable Controller? A solid state device that controls output devices based on input status and a user developed program. Originally developed to directly replace relays used for discrete control.

Where do you Use a MicroPLC? Conveyor control Printed circuit board handling equipment SCADA(Supervisory Control And Data Acquisition) –remote pump/lift station (water/wastewater) –Flow monitoring for leak detection (oil&gas) Strapping machinery / trash compactors Palletizers Compressor control Replace hard-wired relay panels or SBCs Many, many more

Other Types of Control MicroPLCs vs. Relays – above 2/3 relays cost becomes a problem panel space, cost –limited functions limited logic, no math, no application specific instructions timers and counters cost $ to add no communications –difficult to “exchange” data – maintenance/reliability mechanical devices wear out, create and are affected by vibration – expensive to program time consuming, difficult to document, hard to “pass on” logic – difficult to troubleshoot requires skilled technician “race” problems are common and difficult to deal with

Other Types of Control MicroPLCs vs. Custom SBC’s (single board computers) –High design costs Contract or Staff with overhead and maintenance issues associated with each –Repair / Service nightmare for customers Depending on markets served supplier must develop/support services –High level of technical expertise required by technicians Specialized circuit boards require specialized equipment and technical staff –Not readily available through distribution (typically regional) Suppliers sell the controller imbedded, replacement parts are not readily available even in emergency situations –Typically does not meet worldwide standards Certifications cost money, typically a single controller does not warrant the investment. Volumes are not high enough and re-certification on each revision is unrealistic –Typically a “Domestic” product Because of these issues many manufacturers limit themselves to a single market.

Other Types of Controls Competing Control Systems –Relays above 2/3 relays cost becomes a problem limited functions maintenance/reliability expensive to program difficult to troubleshoot –Custom SBC’s (single board computers) High design costs Repair / Service nightmare for customers High level of technical expertise required by technicians Not readily available through distribution (typically regional) Typically does not meet worldwide standards Typically a “Domestic” product

Input Devices Pushbuttons Selector Switches Limit Switches Level Switches Photoelectric Sensors Proximity Sensors Motor Starter Contacts Relay Contacts Thumbwheel Switches 120/230 VAC 24 VDC –Sourcing –Sinking

Output Devices Valves Motor Starters Solenoids Control Relays Alarms Lights Fans Horns Relays –120 VAC/VDC –240 VAC –24 VAC/VDC Triac –120/230 VAC Transistor MOSFET –24 VDC

CR Isolation Barrier Isolation Barrier MEMORY program data High Voltage High Voltage Low Voltage AC Power Supply VAC, 50/60Hz OutputOutput CircuitsCircuits External DC Power Supply or Communications InputInput CircuitsCircuits Central Processor Inside A PLC

PLC Application Considerations Inputs/Outputs –Type, AC, DC, sourcing, sinking, etc. –Number of 10, 16, 20, 32, 156 Memory –Type Flash or Battery backed –Size 1k, 6k, 12k, 16k, 64k Functions required –Instruction set Messaging PID PTO, PWM –Arithmetic –Communications DeviceNet, Ethernet Remote I/O, DH+ –Report generation

PLC’s Come in a Variety of Sizes... Pico –Typically less than 20 I/O Micro –Typically less than 32 I/O Small –Typically less than 128 I/O Medium –Typically less than 1024 I/O Large –Typically greater than 1024 I/O

And a variety of shapes/configurations Packaged –MicroLogix 1000,1200 and 1500 Packaged with expansion –MicroLogix 1200 and 1500 Modular (rack less) –MicroLogix 1200 and 1500 Modular (rack based) –SLC 500 and PLC5 Distributed –SLC 500 and PLC5

Packaged PLC Power supply, inputs, outputs and communication port are enclosed in a single package. Input and output devices are wired individually to the packaged controller.

Packaged PLC With Expansion Base is identical to the standard Packaged PLC, but it also has the ability to drive additional I/O. The most common form of expansion is a block of I/O that uses the same base, or makes use of different types of expansion “modules”.

Modular Rack-Less PLC’s Identical in functionality to rack based PLC’s Typically not as robust (packaging) Typically found on “smaller” (small and medium) sized PLC’s. Will likely become the prevalent form of packaging in the future. ++ ProcessorBase Unit Compact I/O

Modular PLC’s Mix N Match Components –Processors, Power Supplies and I/O are plugged into a rack or chassis –Available in Small, Medium, and Large platforms –Flexibility results in higher costs when compared to packaged

Distributed Rely on communications for EVERYTHING All I/O is connected to the processor through a “High Speed” data link. Typically found on “larger” (medium and large) PLC’s. For certain applications this type of form factor is very advantageous. Usually higher cost for hardware, but much lower cost for system integration. RIO (Remote I/O), DeviceNet are examples of distributed control.

Why use a Micro PLC Performance –Although small in size these products can perform the same tasks as much larger PLC’s Cost –The price range for the entire family: $200-$800 List Reliability –Designed to meet existing industrial design standards UL, CSA, CE Designed & manufactured in ISO9000 facilities International Focus –Standard product available throughout the world

Motor Solenoid 1 Solenoid 2 Solenoid 3 Sensor 1 Sensor 2 Ingredient A Ingredient B Typical PLC Application

Motor Solenoid 1 Solenoid 2 Solenoid 3 Sensor 1 Sensor 2 Ingredient A Ingredient B Operation of Mixer Solenoid 1 –On = Sol 3 is off, and Motor is off, and Sensor 2 is off, and Auto Switch is on –Off = Sol 3 is on, or Motor is on, or Sensor 2 is on Solenoid 2 –On = Sol 3 is off, and Motor is off, and Sensor 2 is on –Off = Sol 3 is on, or Motor is on, or Sensor 1 is on Motor –On = Sensor 1 is on, and Solenoid 2 is off, and Solenoid 1 is off –Off = Solenoid 3 on Solenoid 3 –On = Sol 1 is off, and Sol 2 is off, and Motor has run for 30 sec. –Off = Solenoid 3 has been on for 60 sec.

Terminal Block Input Devices L1 L2 10 COM PLCPLC Isolation Barrier Input Wiring

OUT 1 Output Devices L2 L1 OUT 1 OUT 2 OUT 3 OUT 4 OUT 5 OUT 6 CR L1 PLCPLC Terminal Block Isolation Barrier Output Wiring

Input Scan Program ScanOutput Scan Housekeeping START Each ladder rung is scanned using the data in the Input file. The resulting status (Logic being solved) is written to the Output file (“Output Image”). The status of external inputs (terminal block voltage) is written to the Input image (“Input file”). The Output Image data is transferred to the external output circuits, turning the output devices ON or OFF. Internal checks on memory, speed and operation. Service any communication requests, etc. PLC Operating Cycle