Data Acquistion and Soft Communication.pptx

data acquistion and communication

1. DATA ACQUISITION AND SOFT COMMUNICATION

2. What is Data Acquisition ? Manual Process of Data Acquisition Technician operator checking and record reading value of pressure, temperature and flow transmitter in daily log book

3. What is Digitization? Digitization  refers to the process of converting physical objects into digital format. An example of this would be document scanning, where text from physical paper is converted into PDF or other digital formats, which are then stored in the computer Digitization’s purpose is to encode information in computers by converting from analog to digital format. The process mainly deals with recording data that can eventually be used in digital technologies. This process of digitizing the reality of the world around us has a name:  Data acquisition or, shorter, DAQ . Thanks to this procedure, information can be displayed, analyzed and stored on a computer and used to make better decisions that benefit the business.

4. How does Data Acquisition System work? A data acquisition system (DAS) is a device used to convert physical parameters into digital data that can be read by a computer.  Temperature, light intensity, vibration, gas pressure, fluid movement, and force are a few examples of factors often considered in a DAQ system The basic scheme of DAS is illustrated in Following Fig.

5. Components Of DAQ : Sensors Signal Conditioners Hardware Software

6. Function of DAQ Components Sensors : Sensors are devices that convert physical parameters into electrical signals that can be measured and recorded. They are used to measure physical parameters such as temperature, pressure, flow, and level

7. Function of DAQ Components Signal Conditioners : Signal conditioners amplify, filter, and convert the sensor signals into a form that can be read by the data acquisition hardware.

8. Function of DAQ Components Hardware: Data acquisition hardware is the hardware that is connected between the sensors and the computer. This hardware is either connected to the computer employing a USB port or ethernet port. This component of the DAQ system serves to convert analog signals into digital signals. This component is at the core of all data acquisition systems. 

9. Function of DAQ Components Software: DAQ software provides a user interface for configuring and controlling the data acquisition devices, as well as for viewing and analyzing the data that has been acquired. Specialized data acquisition software required for acquiring, storing, and processing data in a logical format is available

10. DAQ Place in Automation Pyramid

11. System Architecture for Data Acquisition Data Acquisition Hardware RTD Signal Conditionner Resistance Input Data Acquisition Software RS 485 to USB Convertor 4-20 mA Output Sensor Temperature Transmitter RS 485 Soft Communication Modbus RTU Protocol

12. System Architecture for Data Acquisition

13. System Architecture for Data Acquisition

14. Communication Protocol HART (Highway Addressable Remote Transducer) Modbus PROFIBUS (Process Field Bus) PROFINET (Process Field Net) EtherNet /IP (Ethernet Industrial Protocol) Foundation Fieldbus OPC (OLE for Process Control) DeviceNet CANopen Industrial Ethernet AS-Interface (Actuator Sensor Interface) Zigbee MQTT (Message Queuing Telemetry Transport) Bluetooth Wi-Fi

15. What is Modbus ? MODBUS is a communication protocol developed by Modicon in 1979 (now Schneider Electric) used by programmable logic controllers. Modbus transmission of data can be over serial lines or ethernet. Many devices are now Modbus compliant since it's now a widely accepted communication protocol.  Supervisory Control and Data Acquisition  mainly use Modbus (SCADA) to receive data from remote terminal units (RTU) and PLCs. Modbus is an open protocol, meaning that it's free for manufacturers to build into their equipment without having to pay royalties. It has become a very common protocol used widely by many manufacturers throughout many industries. Modbus is typically used to transmit signals from instrumentation and control devices back to a main controller or data gathering system. Modbus communication types Modbus can be grouped into three broad types: Modbus RTU – Serial Modbus ASCII - Serial Modbus TCP – Parallel Ethernet

16. Modbus RTU Working Modbus is transmitted over serial lines between devices. The simplest setup would be a single serial cable connecting the serial ports on two or more devices, a Master and Slaves.  The data is sent as series of ones and zeroes called bits. Each bit is sent as a voltage. Zeroes are sent as positive voltages and a ones as negative. The bits are sent very quickly. A typical transmission speed is 9600 baud (bits per second). A Modbus RTU operates a Master to slave structure. A Modbus master can connect with up to 32 slaves and exchange data. Each slave has its own 8-bit device address, often known as a unit number or Device ID Number or Sr.Number .

17. Modbus RTU Working The address of the slave for whom the communication is intended is included in the packets transmitted by the master. The slave must only answer if its address is recognized, and it must do so within a specific amount of time, or the master will consider it a "no response" error

18. Modbus RTU Working A slave is any peripheral device that analyzes data and delivers a response message to the master using Modbus, such as an I/O transducer, valve, network drive, or other measuring devices. The communication media for an RTU network is serial, either using RS232, RS422, or RS485. Modbus Protocol | Physical connection of RS232, RS485, RS422 using a DB9 cable

19. Modbus Register addressing The Modbus protocol is based on the concept that Modbus slaves hold their data in a series of defined status flags and registers, with defined addresses. A number of flags and registers are set aside for a number of purposes: Discrete Outputs (Coils) – Digital Output Discrete inputs (contacts) – Digital Input Input registers – Analog Input Holding Registers Holding registers – Analog Output Holding Register

20. Modbus Register addressing Discrete Outputs (Coils): Coils are one-bit registers used as outputs. They are both read and write registers Discrete inputs (contacts): Discrete inputs are bit contact registers, and they can only be read. They can best be described as the contacts in PLC programming. Input registers: Inputs registers are 16-bit registers used for inputs. They are read only Holding registers: Holding registers are 16-bit registers that are both read and write. They are the most universal register as they can be used for inputs, outputs, and for holding any kind of data.

21. RS 485- Daisy Chain Wiring Each device [MASTER or SLAVE] has a connection port with 2 terminals that are used to communicate with that particular device over MODBUS RTU – RS485. These terminals are mostly marked as A [or DATA +] and B [or DATA -]. The cabling is done such that all these devices are connected in parallel. This means that all the A terminals should be connected together and all the B terminals should be connected together

22. RS 485- Setting Communication Parameter Baud rate Set this parameter based on the baud rate of the connected device. The value can be  1200 ,  2400 ,  4800 ,  9600 ,  19200 , or  115200 . Parity Set this parameter based on the parity mode of the connected device. The value can be  None ,  Odd parity , or  Even parity . Stop Bit Set this parameter based on the stop bit of the connected device. The value can be  1  or  2 .

23. RS 485- Modscan / Modbus Tester Software Tools to check the communication

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