PLC VS SCADA

Structured text Structured Text is a programming language and is primarily designed for PLCs and Structured Text is ST or STX. Structured Text Language is the simplest language of PLC and this language does not need to be written for PLC programming background. And this language does not require PLC programming software to create structured text programs. Basically structured text is a text based language in which this language writes a simple text file and copy and paste into the PLC project. Structured text languages ​​have common advantages Text based language Light language No programming background required Cost effective What is Structured Text? Structured Text is the programming language of PLC and is a text based language. Basically structured text is known as ST or STX. What is the use of structured text? Basically the use of structured text is to program the PLC.

PWM  PWM is pulse width modulation Pulse width modulation reduces the average power delivered by an electrical signal by converting the signal into discrete parts. In the PWM technique, the signal’s energy is distributed through a series of pulses rather than a continuously varying (analog) signal Pulse width modulation or PWM is a commonly used control technique that generates analog signals from digital devices such as microcontrollers.

Ladder logic for controlling the running state of the single phase motor by pressing START and STOP pushbuttons

PTO function used in PLC systems   PTO (Pulse Train Output) PTO is for accurate positioning or precise velocity-control. A pulse rotates the motor by a fractional amount. Changing of frequency while duty cycle remains at 50%. T (duration) is varied. The control is done from software. The ratio of T (OFF) to T (ON) can be fixed at 50%:50%. Motion control: The open loop control of stepper motor the stepper motor amplifier ensures a constant distance increment for each pulse received. The duration of the increment is given by the frequency of the pulse. This is more familiar to use than PWM, used for stepper motors and servo motors. Position and speed can be controlled even if only open loop control is used. The Programmable Logical control provides for motion control. With the S7-1200 FW4.2 a new block is available that can set the frequency. A user program can manipulate directly the frequency. This is helpful for working speed control of variable speed drives instead of using analog co

OSI/ISO reference model in communication system Layer 1 (Physical): This layer considers only the physical aspects of a network; the cables, converters, interconnecting devices, etc. Layer 2 (Data-link): This layer concerns itself with how Layers 1 and 3 work together. Layer 3 (Network): This layer provides an addressing scheme for routing of data and messages. Layer 4 (Transport): This layer makes sure that messages get to their correct destination. Layer 5 (Session): This layer handles the actual connections between systems. Layer 6 (Presentation): This layer deals with the way different systems represent data. Layer 7 (Application): This layer concerns itself chiefly with the software applications used on a computer screen

Advantages of Foundation Fieldbus FOUNDATION fieldbus provides an open specification for both communications and the control application. FOUNDATION fieldbus distributes control functionality across the bus, making maximum use of local intelligence to improve performance and reduce total system cost. Devices are required to be interoperable, providing the user with tools to implement a control system with products from multiple manufacturer switch out custom programming

Benefits And Advantages of Fieldbus Benefits of Fieldbus Reduced Cabling Simple Configuration Less maintenance Reliability Flexibility Advantages of Fieldbus High speed Interoperability with other field bus device Advanced diagnostics Reduce wiring Two way communication

Foundation Fieldbus H1  A fieldbus is an all-digital, serial two-way, multi-drop communication System. Which will be used in industry to replace the existing 4 -20mA analog signal. H1 (31.25kbps)interconnects field equipment(Sensors, Actuators & I/O). HSE (High Speed Ethernet, 100mbps) provides integration of high speed controllers, subsystems (via Linking Device) and data servers and workstation. A fieldbus consists of two wires. The digital signal can be transferred as a voltage difference between the wires or as a current value. Fieldbus allows “multiple variables” from each device to be brought into the control system for archiving, trend analysis, process optimization, reporting, predictive maintenance and for asset management. Fieldbus H1 Multi-Drop wire pair with Power and Signal on same cable. Support Intrinsic Safety. Function Blocks built into Field Devices. Control on the Wire – single loop integrity Distance up to 1900 meters Add Repeaters to extend > 1900 meters Max

HART Protocol The HART (Highway Addressable Remote Transducer) Communication Protocol directly contributes to these business goals by providing cost savings in: Commissioning and installation Plant operations and improved quality Maintenance Products that use the HART protocol to provide both analog 4-20A and signals provide flexibility not available with any other communication technology The HART Communication Protocol is based on the Bell 202 telephone communication standard and operates using the frequency shift keying (FSK) principle. The digital signal is made up of two frequencies: 1,200 Hz and 2,200Hz representing bits 1 and 0, respectively. Sine waves of these two frequencies are superimposed on the direct current (dc) analog signal cables to provide simultaneous analog and digital communications as. Because the average value of the FSK signal is always zero, the 4-20mA analog signal is not affected. HART devices can operate in one of two network configurations Point-to-Point

OPC (Object linking and embedding for Process Control) OPC (Object Linking & Embedding for Process Control) is the world’s most popular standards-based data-connectivity method. OPC is the software interface standard that allows windows programs to communicate with the industrial hardware devices. The OPC server is the software program that converts the hardware communication protocol used by PLC into OPC protocol. The OPC is an industry standard set up by OPC foundation specifying the software interface to a server that collects data produced by field devices and PLC OPC resolves this by making it unnecessary for the Data Sink to know anything about how the Data Source communicates or organizes its data. OPC eliminates the need for custom drivers between each new application and Data Source. Using OPC greatly simplifies integration because once an OPC Connector for a particular Data Source is configured, all OPC enabled applications can start sharing data with that Data Source wit

Difference RS-232, RS-485, RS-422

HART Protocol With Reference To OSI Model HART protocol The HART (Highway Addressable Remote Transducer) Communication Protocol directly contributes to these business goals by providing cost savings in: Commissioning and installation Plant operations and improved quality Maintenance Products that use the HART protocol to provide both analog 4-20A and signals provide flexibility not available with any other communication technology. The HART Communication Protocol is based on the Bell 202 telephone communication standard and operates using the frequency shift keying (FSK) principle. The digital signal is made up of two frequencies: 1,200 Hz and 2,200Hz representing bits 1 and 0, respectively. Sine waves of these two frequencies are superimposed on the direct current (dc) analog signal cables to provide simultaneous analog and digital communications. Because the average value of the FSK signal is always zero, the 4-20mA analog signal is not affected. HART Data  Digital data 35-40 valuabl

Modbus (ASCII/RTU) Communication Standard Modbus Modbus is a serial communications protocol originally published by Modicon (now Schneider Electric) Modbus is an open data communication protocol Modbus is open structure, flexible, independent of the physical layer  Modbus is supplied by many SCADA and HMI software Modbus is 2 serial transmission modes  ASCII - 10 bits  RTU (Binary) - 11 bits Modbus is Communication interface  RS-232/485 Ethernet(TCP/IP) Application Used to establish master-slave/client-server communication between intelligent devices Openly published and royalty-free Modbus enables communication between many (approximately 247) devices connected to the same network Communication between MODBUS devices MODBUS devices communicate using a master-slave technique in which only one device (the master) can initiate transactions (called queries). The other devices (slaves) respond by supplying the requested data to the master A slave is any peripheral device (I/O transducer, v

Benefits Of Automation Automation Automation is Technique which is used to reduce. I cost and improve quality. Automation can increase manufacturing speed and reduce costing Automation can lead to product having consistent quality To Automation is a Technology concerned. with application of mechanical, electronic and computer-based system to operate and control system Benefits Of Automation High productivity  Although many companies hire hundreds of production workers for a up to three shifts to run the plant for the maximum number of hours, the plant still needs to be closed for maintenance and holidays. Industrial automation fulfills the aim of the company by allowing the company to run a manufacturing plant for 24 hours in a day 7 days in a week and 365 days a year. This leads to a significant improvement in the productivity of the company. High Quality Automation alleviates the error associated with a human being. Further, unlike human beings, robots do not involve any fatigue, whi