Introduction to Automatization

Automation Pyramid

Action Level / Sensing (cell level): first level of instrumentation. It is formed by measuring elements (sensors) and control (drives) distributed in a production. They are more related items with the productive process because the actuators are responsible for executing orders of control elements for modify the productive process, the sensors measure variables in the production process such us: liquid level, flow, temperature, pressure, position. As examples of actuators have engines, valves, heaters.

Control level (field level): at this level the elements capable of managing the actuators and sensors of the previous level, such as PLCs or application specific equipment based on microprocessors and robots, machine tools or motor controllers are located. These devices are programmable and allow actuators and sensors work together to be able to perform the desired manufacturing process. Devices of this level of control with the lower-level sensing/action possess sufficiently important to make production processes themselves. . It is important to having good characteristics of interconnection to be bonded to the upper level (supervision), usually through fieldbus.

Supervision Level (Ground level): at this level is possible to visualize how they are performing plant processes, and through SCADA (Supervisory Control and Data Acquisition) environments have a "virtual image of the plant" so that it can go so detailed or summary screens by being able to have a "virtual panel" where possible alarms, faults or alterations in any of the processes carried out are displayed.

Level Management (factory level): This level is characterized by: Manage the complete company production, communicate different plants, maintain relations with suppliers and customers, provide the basic slogans for the design and production company, it PCs, workstation. A widely accepted basic axiom is: "The CIM has to be planned" top down "(" top-down "), but should be implemented" bottom up "(" bottom-up "). s and servers of various kinds are used.

Concepts Automatism: System that allows executing one or more actions without

intervention manual.

Automation: Application of automated systems performing a process

Elements of an automatic system:

Power source: The operations and movements of automatic systems represent a energy expenditure that must be provided by an external medium. Often it referred to that power source that supplies power to working organs acting on the process. The functions of the automatic system also need a energy support.

Organs Command / Control: Represents the system that decides when to perform actions that actions to apply, and where appropriate, the value must take some of the parameters defining an action or task.

Sensory organs: These are systems whose mission is to capture or measure certain values or magnitudes during operating the process. these organs provide information to control members so that they can split accordingly.

Action: action on the means or process operations are often. They could be repeated indefinitely. Usually human actions that can be replaced by mechanical actions taken by the working bodies.

Monitoring and Control Techniques

Discrete or discontinuous processes:   The magnitudes that determine the evolution of the process change discrete or discontinuously and often take only certain values. The system evolves by events. These processes are also known as discrete event processes. In the discrete processes it acts on specific objects also called discrete elements.

Example: carrier tape

Continuous processes: The magnitudes that determine the evolution of the process change continuously over time. There is a similarity between the ongoing processes and systems analogelectronics.Example:

The tape will be driven to the right if S1 detects the presence of an object at the beginning of it, and it stops when S2 detect the object. The tape will be driven to the left if S2 detects the presence of a object at the beginning of it, and stop when S1 detects the object. Magnitudes that define the evolution of the process are: detection object at the beginning; detection of the object at the end and start or stop the engines. These quantities can only take two values, detected or not detected, running or stopped

Batch processes: Are discrete processes that involve more than one element or blank for processing in a single product.

Automatic regulation:  Action mechanisms that allow for a continuous process to magnitudes that reaches a certain value. When this value remains constant over time it says it is a problem of regulation When this value varies over time it says it is facing a servomechanism problem

Example: Regulation problem, constant temperature in an installation

Controlling an automation system: Sequential Control Industrial automation concept is usually applied to control discrete processes. The control elements are discrete and process information. They provide discrete commands on the working bodies. Control systems acquire a sequential structure:The process is divided into a number of stages.- Each state is activated and deactivated sequentially.- Each active state has associated a series of actions.

• Many times, in controlling a process they are involved magnitudes continuous nature and magnitudes of discrete nature. In these cases it is necessary to apply both strategies as secuentials regulation. It is what is known hybrid control.

Servomecanism problem: Moving a camera to follow a object

Example:

Open Loop Control: The command or control organs acting on the process according to previously established targets. Does not exist transmission of information from the process control organs

Example: heating food in the microwave.

Example: Any problems or servocontrol.

Types of Sequential Control: asynchronous State transition occurs only due to changes in process variables.

Example: control of a motor via a relay.

Closed loop control: Control systems consider the information received from the process to modify them depending on the action to take.

Example: processes controlled by microprocessors

AUTOMATIZATION SYSTEMS

Mechanical Automation Systems: Usual mechanisms: Gears, belts, levers etc.

Examples: lathes, milling machines, Mechanical Watches, etc.

Neumatic Automation Systems: Usual mechanisms: compressors, valves, pistons

Examples: Railways Brakes, tire machines shot etc

Synchronous: Transitions in the state variables and occur on a synchronized by pulses of a fixed frequency clock.

The loop execution is synchronized by the system clock, this implementation structure allows sequential control systems.

Hydraulic Systems Automation: It has similar characteristics to the pneumatic mechanisms, only the hydraulic control has a response time of less pneumatic control.Examples: Motor vehicle steering, hydraulic presses

Electric Automation and Electronics: It is the most common at present, electric actuation systems They are well known, motors, electromagnetic actuators. The electric control is usually implemented using relays. The electronic control may be implemented by components electronic or by discrete digital logic systems programmable gate array (FPGA). The most widespread method is electronic automatization microprocessor.

Microprocessor control: The microprocessor allows the execution of a program that is running in sequence, this sequence is performed cyclically what is known running control loop.

Blocks diagram

PLC SYSTEMS: PLC: programmable electronic machine no computer staff, to comply in an industrial environment, real-time functions logical, combinatorial and sequential automatic. It is modular system with a CPU and input /output.

Cycle control / treatment PLC:- Read inputs- Calculate outputs-Write OutputsType of Operations:- Entrance/ Output- Logical: AND, OR- Timers and features: TIM, CNT- Arithmetic- JumpMemory:- Operating SW (ROM) is dedicated to fixed tasks cycle. (Read inputs, throw out, timing).-Memory Program (EPROM / RAM): It stores and associates variables Input / Output.-Data -Memory: Stores variables associated with inputs / outputs

Entrance Exit: are signals of 8/16 modules E / S. These modules translate signal values and also ensure galvanic isolation

Operating cycles: During operation of the controller there are two phases:

Phase system-Check In / Out- Check memory- Initiation of timers- Initiation of Accountants

Treatment Phase: There may be different Modes (beginning of the cycle) Modes:

- Direct: The program runs over and over repeatedly and cyclically.

- Synchronous: Periodically the program is started.

- Auto sync: It requires input transitions to generate interrupts to the CPU. So only input changes the outputs are recalculated

Management Input / Output

- Acquisition block, block issue: All entry at a time are read and then all outputs are written to time.

- Acquisition block direct release: They read all input and outputs are updated as They are calculated (no need to allocate memory for output data, as is written directly).

- Direct procurement, direct broadcast: Readings are taken equations are evaluated and updated the outputs individually PLCs typically have a Watchdog if it is not reset before some time generates an interrupt.

Programation: It is made using a control unit or through a computer.

Exists several programming languages:

 RLL (Relay Ladder Logic): It's a graphical language by screen.

ASSEMBLER: basic instructions are given to the PLC.

LD 200

AND 001

OR 002

OUT 200

END

HIGH-LEVEL LANGUAGES: “GRAFCET" that allow

Logic gates

Logic equations

Concurrent actions

AUTOMATAS NETWORK: Currently it is meant to introduce automata networks communications. There are also modular PLCs are expanded by adding modules.

Field Buses

System AS-I data transmission and orders for sensors and actuators.

Profibus: Allows networking of PLCs, set various master-slave process monitoring hierarchies. Bus topology

Interbus: open system with ring topology allows exchange of information between devices from different manufacturers

SIMATIC S7-200

Inputs & Outputs

CPU Memory: Data Types and addressing the data memory is divided into two distinct areas, Area Data Objects.

You could access data in different memory areas of the CPU in byte, word or double word.

To access a bit in a memory area, you specify the direction thereof, which comprises an area identifier, the byte address and the bit number.

Example: The figure shows: I3.4 (I = input, 3 = byte 3 4 = bit 4)

The address of a byte, word or double word of data in the memory of the CPU is indicated similarly to the direction of a bit. The latter consists of an area identifier, size data and the start address of the byte value

Example:

Addressing the process image of the inputs (I) Bit I [byte address]. [Bit address] I0.1 Byte, word, double word I [size] [initial byte address] IB4

Addressing the process image of the outputs (Q) Bit Q [byte address]. [Address. Bit] Q1.1 Byte, word, double word Q [size] [tinitial byte address] QB5

Addressing Memory variable (V) Bit V [byte address]. [Address. Bit] V10.2 Byte, Word, Double Word V [size] [initial byte address] VW100

Addressing memory area (M) Bit M [byte address]. [Address. Bit] M26.7 Byte, word, double word M [size] [initial byte address] MD20

Addressing the Special Memory (SM)Bit SM [address. byte]. [bit address] M0.1 Byte, word, double word SM [size] [initial byte address] SMB86

Addressing the area of timers (T): Two variables associated with a timer: • Current value; • Bit Timer (bit T)

Accessed using: T + timer number. Depending on the operation used, the value is accessed or bit timer

Accessed using: T + timer number. Depending on the operation used, the value is accessed or bit timer

Accessed using the counter address (C + number counter) .Depending of operation used, the value is accessed or bit counter

TYPES OF CONTACTS (read inputs)

Coil Types (writing outputs)

Spetial brands

PROGRAMMING

Output Enable 1 if current flow at the input 0.1