PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

What is a Programmable Logic Controller?1. A programmable logic controller (PLC) or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or lighting fixtures. (www.wikipedia)

2. A modern programmable logic controller is usually programmed in any one of several languages, ranging from ladder logic to Basic or C. Typically, the program is written in a development environment on a computer, and then is downloaded onto the programmable logic controller directly through a cable connection. (www.wisegeek.com)

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

BLOCK DIAGRAM OF PLC

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

BLOCK DIAGRAM OF PLC

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

What is the ROLE of Programmable Logic Controller?In an automated system, the PLC is commonly regarded as the heart of the control system. With control application program (stored within the PLC memory), in execution, the PLC constantly monitors the state of the system through the field input devices’ feedback signal. It will then based on the program logic to determine the course to be carried out at the field output devices.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

What are the PLC input devices?Intelligence of an automated system is greatly depending on the ability of a PLC to read in the signal from various types of automatic sensing and manual input field devices.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

What are the PLC output devices?An automatic system is incomplete and the PLC system is virtually paralyzed without the means of interface to the field output devices.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

Conventional Control Panel Typical PLC Control Panel

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

What are the advantages of a PLC?1. The wiring of the system usually reduces by 80% compared to conventional relay control system.

2. The power consumption is greatly reduced as PLC consume much less power.

3. The PLC self diagnostic functions enable easy and fast troubleshooting of the system.

4. Modification of control sequence or application can easily be done by programming through the console or computer software without changing of I/O wiring, if NO additional INPUT or OUTPUT devices are required.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

What are the advantages of a PLC?5. In PLC System spare parts for relay and hardware timers are greatly reduced as compared to conventional control panel.

6. The machine cycle time is improved tremendously due to the speed of PLC operations is a matter of milliseconds. Thus, productivity increases.

7. It cost much less compared to conventional system in situation when the number of I/Os is very large and control functions are complex.

8. The reliability of the PLC is higher than the mechanical relays and timers.

9. An immediate printout of the PLC program can be done in minutes. Therefore, hardcopy of documentation can be easily maintained.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PLC Programming Requirements1. Boolean Logic and Relay Logic.

2. Basic Programming Knowledge.

3. Physical Components vs. Program Components.

4. Wiring skills and technical know-how.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PLC Programming Requirements1. Boolean Logic and Relay Logic.

Since the relays in a machine perform some type of control operation, it can be said that they perform logical function. As with logical functions, these control circuits must consist of the fundamental AND, OR, and INVERT logical operations. Relay coils, N/C contacts, and N/O can be wired to perform these same fundamental logical functions. By properly wiring relay contacts and coils together, we can create any logical function desired.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

AND Function

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

OR Function

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

AND OR Function

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

AND OR Function

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

OR AND Function

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

OR AND Function

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PLC Programming Requirements2. Basic Programming Knowledge.

The IEC 1131 standards were developed to be a common and open framework for PLC architecture, agreed to by many standards groups and manufacturers. They were initially approved in 1992, and since then they have been reviewed as the IEC-61131 standards. The main components of the standards are:a.IL (Instruction List) – This effectively mnemonic programmingb.ST (Structured Text) – A BASIC like programming languagec.LD (Ladder Diagram) – Relay logic diagram based programmingd.FBD (Function Block Diagram) – A graphical dataflow programming methode.SFC (Sequential Function Charts) – A graphical method for structuring programs.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PLC Programming Requirementsa. IL (Instruction List)

Is defined as part of IEC 61131 standard. It uses very simple instructions similar to the original mnemonic programming languages developed for PLCs. It is the most fundamental level of programming – all other programming languages can be converted to IL programs. Most programmers do not use IL programming on a daily basis, unless they are using hand held programmers.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PLC Programming Requirementsb. ST (Structured Text)

If you know how to program in any high level, such as Basic or C, you will be comfortable with Structured Text(ST) programming. ST programming is part of the IEC 61131 standard. The program is called main and is defined between the statement PROGRAM and END_PROGRAM. Every program begins with statements the define the variables.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PLC Programming Requirementsb. ST (Structured Text)

Structured Text Program Example

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PLC Programming Requirementsc. Ladder Diagram

Is a language which is composes program using relay symbols as a base in an image similar to a hard-wired relay sequence.

The ladder diagram is program is constructed by units called “rung”. A rung is defined as one network which is connected to each other.

The size of any “rung” is limited to 11 lines x 12 columns.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PLC Programming Requirementsc. Ladder Diagram

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PLC Programming Requirementsd. Function Block Diagram Programming.

Is a bonafide computer programming language, it is highly formalized with strict rules for how diagrams are to be built. Directed lines are used to connect input variables to function inputs, function outputs to output variables, and function outputs to inputs of other functions. These blocks portray mathematical or logical operations that occur in time sequence. They do not represent the physical entities, such as processors or relays, that perform those operations. Each block is therefore a black box. The rules require the logical sequence to go from left to right and top to bottom.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PLC Programming Requirementsd. Function Block Diagram Programming.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PLC Programming Requirementse. Sequential Function Chart (SFC).

Sequential function chart (SFC) is a graphical programming language used for PLCs. The SFC standard is defined in IEC 848, "Preparation of function charts for control systems", and was based on GRAFCET(GRAphe Fonctionnel de Commande des Etapes et Transitions).

It can be used to program processes that can be split into steps.

Main components of SFC are:

1. Steps with associated actions2. Transitions with associated logic conditions3. Directed links between steps and transitions

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PLC Programming Requirementse. Sequential Function Chart Programming.

Sequential Function Chart of a Stamping Press

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)2. Basic Programming Knowledge.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

ANB and ORB

Programming Using Instruction List

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

ANB and ORB

Programming Using Instruction List

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

ANB and ORB

Programming Using Instruction List

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

ANB and ORB

Programming Using Instruction List

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

ANB and ORB

Programming Using Instruction List

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

1. Problem: Convert the following ladder diagram to its equivalent mnemonic codes:

Programming Using Instruction List

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

Using FX-Series Mitsubishi

Programming Using Instruction ListUsing OMRON SYSMAC Using ALLEN-BRADLEY

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)Programming Using Instruction List

2. Problem:

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

Using FX-Series Mitsubishi

Programming Using Instruction ListUsing OMRON

SYSMACUsing ALLEN-BRADLEY

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)Programming Using Instruction List

3. Problem:

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

Using FX-Series Mitsubishi

Programming Using Instruction ListUsing OMRON

SYSMACUsing ALLEN-BRADLEY

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

A Systematic Approach of Control System Design Using A Programmable Logic Controller

1. Determine the Machine Sequence of Operation.

2. Assignment of INPUTS and OUTPUTS.

3. Writing of the Program.

4. Programming into Memory.

5. Running the System.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)A Systematic Approach of Control System Design Using A Programmable Logic

Controller

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)Programming Using Instruction List

1. Problem: In a company, an electric bell is used as a signal to tell the staff that it is time to start work, go for tea break, go for lunch and go home. A switch is used to activate the bell. The bell rings when the switch is pressed. It will go off when the switch is released.

Write the instruction for the given situation using mnemonic code.

Solution:

Control Circuit

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)Solution:

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)2. Problem: A siren will sound when a switch is pressed. It will continuously ring even when the activating force is removed. It will go off when the switch is reset.

Write the instruction for the given situation using mnemonic code.

Solution:

Control Circuit

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)Solution:

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)3. Problem: In a chemical plant, an indicating lamp will be lighted when the pressure and the temperature rise above a certain level. These two conditions are simulated by using push-button switches PB1 and PB2. In other words, when both PB1 and PB2 are pressed, the lamp will be lighted. When either one of them is released, the lamp will go off.

Write the instruction for the given situation using mnemonic code.

Solution:

Control Circuit

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)Solution:

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)4. Problem: In a production line, an indicating lamp will be lighted whenever an operator presses a push-button. This is to capture the attention of the line leader whenever they encounter a problem. Here, three stations are simulated using push-button switches PB1, PB2 and PB3 respectively.

Write the instruction for the given situation using mnemonic code.

Solution:

Control Circuit

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)Solution:

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)5. Problem: In an electrical parts warehouse, a normally-closed limit switch is used to send a signal to the burglar alarm when the door is opened. The alarm will not sound if the door is closed. The burglar alarm system is activated or de-activated by a key selector switch.

Write the instruction for the given situation using mnemonic code.

Solution:

Control Circuit

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)Solution: (Push-button Switch)

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)Solution: (Using a Push-button and Toggle Switch)

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)Solution: (Using a Toggle Switch)

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)1. Problem: Write a program using FX-1S plc for a normally open pushbutton controlling a holding coil.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)2. Problem: Write a program using FX-1S plc for a normally closed pushbutton controlling a holding coil.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)3. Problem: Write a program using FX-1S plc for application of a holding coil.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)4. Problem: Write a program using FX-1S plc for an ON priority circuit.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)4. Problem: Write a program using FX-1S plc for an ON priority circuit.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)5. Problem: Write a program using FX-1S plc for an Interlock or Inhibit Circuit.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)6. Problem: A company wants their pumping station to be automatically operating. They want a system that has an alternate operation of two pumps. A float switch initiates automatic operation. Assuming the tank is empty, Motor 1 starts. When the water level reaches high level, float switch activates (opens). Motor 1 drops out once the water level decrease below high level

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)6. Solution:

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)6. Solution:

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

What is a Solenoid Valves?A solenoid valve is an electromechanical valve for use with liquid or gas.

The valve is controlled by an electric current through a solenoid: in the case of a two-port valve the flow is switched on or off; in the case of a three-port valve, the outflow is switched between the two outlet ports. Multiple solenoid valves can be placed together on a manifold. (www.wikipedia.com)

1. Valve Body2. Inlet port3. Outlet Port4. Coil/Solenoid5. Coil Windings6. Lead Wires7. Plunger8. Spring9. Orifice

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

What is a Solenoid Valves?

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

What is a Solenoid Valves?

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

What is a Solenoid Valves?

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

What is a Solenoid Valves?

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)

What is a Solenoid Valves?

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)7. Problem: In a printing firm, a cutter is used to cut the side edge of papers. This cutter is controlled by pneumatic cylinder. For the safety of the operator, the cutter will move down only when both push-button switches PB1 and PB2 are pressed and also a safety cover must be closed. This safety cover is closed manually and a limit switch is used to detect the closed position. When one of the push-button is released or when the safety cover is opened, the cutter will immediately return to its top position. The cylinder is controlled by a single solenoid spring return valve.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)7. Solution:

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)7. Solution:

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)8. Problem: A huge steel door is installed in a deep mining tunnel. This door may be opened or closed by two sets of push-button switches. One set from inside and the other set from outside. The sliding unit is controlled by a double solenoid valve.

There are two control methods being used, namely:a.Direct controlb.Indirect control

Try solving using these two methods.

PROGRAMMABLE LOGIC CONTROLLER

PROGRAMMABLE LOGIC CONTROLLER (PLC)8. Solution: