International Journal of Computer Networking, Wireless and Mobile Communications (JCNWMC) ISSN 2250-1568 Vol.3, Issue 1, Mar 2013, 111-116 TJPRC Pvt. Ltd. WIRELESS DATA ACQUISITION SYSTEM FOR PHARMACEUTICAL AND CHEMICAL INDUSTRIES USING LOAD-CELL NAYEEM MUDDIN KHAN D 1, GNL RAVI TEJA 2, R BHARGAVA KRISHNA 3 & RAJESH SINGH 4 1,2,3 Robotics Engineering, University of Petroleum and Energy Studies, Dehradun, India 4 Electronics Electrical and Instrumentation Engineering,University of Petroleum and Energy Studies, Dehradun, India ABSTRACT Data acquisition system possesses various applications in numerous fields. Pharmaceuticals companies and chemical industries find importance of data acquisition system while acquiring and storing data related to weights and quantities of different chemicals and compounds. Such a system uses a load cell to measure the weights/volume of the chemicals and stores the data in a computer for later reference. These modules are also used in condiment stores where the weight/quantity of the commodity is found using the load cell, data is sent to the computer which then decides the cost of it. Use of such system reduces the need of manually creating a database which may lead to errors. This paper describes a similar system with an additional feature of wireless communication using ZigBee protocol. The weight measured, can be monitored from long distance by sending it to another module through wireless system which is then sent to the database. Low power consumption, low cost, accurate measurement and the flexible structure are the characteristics of this module. KEYWORDS: Load Cell Sensor, Central Computing Unit, ZigBee Transceiver, Strain Gauge WSN Algorithm INTRODUCTION Wireless Sensor networks are at a high demand in the industries with hazardous working environments. A combination of embedded and wireless system allows data transmission among different sensor nodes. This setup does not require any communication medium like WLAN or cellular network for communication. The computing unit at each node is a microcontroller which processes and transmits the data from one node to the other creating a personal network. The network thus developed helps in data monitoring and controlling the physical quantities of remote locations in accurate and safe way [1]. This technology has been exploited by different industries where monitoring the process is a difficult but important task. One such application has been illustrated in this paper. The data acquired from load cell is transmitted to various stations inside the network where this data can be analyzed and even stored Most of the industries such as chemical and pharmaceutical, steel plants and many more require storing and creating a database of features of their product. Load cells are the sensors used to measure the weight of the products. Sometimes it becomes difficult to monitor the weight in hazardous conditions. In cases such as monitoring the mass of a radioactive material used in the reactor it s not feasible for every person to do so, whereas one person can check the mass (at a station) and send it to other stations wirelessly through the module described in this paper. HARDWARE DEVELOPMENT Each module has an independent transmitting and a receiving development board. The transmitting board displays and sends the data from the load cell which is displayed and the receiving end. Hardware used in each of the development board are Atmel micro controller, LCD and a Zigbee module. The transmitter has a load cell sensor module attached to it.
112 Nayeem Muddin Khan D, Gnl Ravi Teja, R Bhargava Krishna & Rajesh Singh Transmitter The block diagram gives the representation of transmitter circuit. It consists of a Load Cell trainer module, on board power supply, Atmega 32, LCD, ZigBee transmitter. On board power supply converts the applied voltage to 5V which is required for the microcontroller, MAX 232, LCD and ZigBee to operate. The Load cell trainer module has inbuilt power supply. The micro controller receives the data from the sensor with the help of DB9 connected to the module. The weight is acquired by the controller using UART protocol via MAX232. Once the weight in analog is received it is converted into digital signal using the inbuilt Analog to Digital Converter (ADC) in the micro controller. The converted digital signal is transmitted to the receiving board via ZigBee transceiver. Figure 1: Block Diagram of Transmitter Circuit Figure 2: Transmitter Circuit Receiver The figure below shows the block diagram of the receiver module which is really is the same circuit. An on board power supply is developed which supplies 5V to microcontroller and LCD. Transmitted data is received through this circuit and displayed on the screen. Thus the observer would be able to get the data from the plant area to the control room. Figure 3: Block Diagram of Receiving Circuit
Wireless Data Acquisition System for Pharmaceutical and Chemical Industries using Load-Cell 113 Figure 4: Receiving Circuit Load Cell Sensor Measurement of weight/load can be done with many sensors with a proper signal conditioning. The load is measured using a strain gauge bridge circuit having four arms. Strain gauge works on the principle that when a conductor is subjected to strain due to the applied load the resistance varies. The strain gauges are attached at places where the beam is stressed the most. When load is applied the change in dimension which is essentially strain is measure by these gauges and corresponding change in the resistance of the bridge circuit gives out a voltage. In this project the load cell module (Model No: ITB - 04CE) developed by VI Microsystems Pvt. Ltd, was used. The module consists of cantilever beam, LED display, power supply. This module can measure weight up to 5kg which can be displayed on the LCD Screen. Power Supply An on board power supply unit supplies electrical signal for the devices to run. This unit converts the AC supply to DC supply that is required to drive the components on the board. All the ICs generally work on 5V supply. For this a power supply was developed using a bridge rectifier for the conversion of AC signal to DC to get the output DC voltage of 12V which is further reduced using a voltage regulator to 5V. The unit gives an output of 5V and 500 ma current for the components on nodes to work. Both the transmitter and receiver have on board power supply. Figure 5: Load Cell Setup
114 Nayeem Muddin Khan D, Gnl Ravi Teja, R Bhargava Krishna & Rajesh Singh ATmega 32 The ATmega32 is a low-power CMOS 8-bit microcontroller based on the AVR RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega32 achieves throughputs approaching 1 MIPS per MHz, allowing the system designed to optimize power consumption versus processing speed. ZigBee Transceiver This is the radio frequency receiver module, which can facilitate the OEM designers to design as per their application in the quickest ways. The circuit is designed with SMD components and the module size is small enough to be able to be fitted in almost any application. These modules are based on IC CC2500 by Texas Instrument. It works at frequency of 2.4GHz. LCD The LCD unit receives character codes (8 bits per character) from a microprocessor or microcomputer, latches the codes to its display data RAM (80-byte DD RAM for storing 80 characters) transforms each character code into a 5*7 dotmatrix character patterns, and displays the characters on its LCD screen. MAX 232 Max 232 (level converter): The MAX232 is a dual driver/receiver that includes a capacitive voltage generator to supply EIA-232 voltage levels from a single 5-V supply. Each receiver converts EIA-232 inputs to 5-V TTL/CMOS levels. These receivers have a typical threshold of 1.3 V and a typical hysteresis of 0.5 V, and can accept ±30V inputs. Software Development The required coding was done in AVR Studio4 using embedded C programming language. Transmitting end coding included reading and converting the analog signals from the load cell, displaying and then transmitting them. At the receiving end an embedded code is developed for the microcontroller to receive the data and display it. For the whole process to run a software development procedure has been followed. The following steps are involved in the software development: Coding/debugging Compiling Burning Coding / Debugging The process of designing a problem using a high level programming language such as C, Java or assembly language is known as coding. Coding is done to create a set of instructions or an algorithm for the microcontroller to perform the specific task. In this case the task was to read the data from the sensor and transmit them wirelessly to a displaying device for the observer to acquire or monitor it. For this project Load-Cell WSN algorithm was coded in AVR studio4 using embedded C programming language. Compiling A microcontroller understands only the machine level language. Therefore a C code must always be converted into machine level language for the controller to understand. A compiler converts the C program into machine level language. Apart from the main code there are source codes developed for supporting the protocol to run and are merged
Wireless Data Acquisition System for Pharmaceutical and Chemical Industries using Load-Cell 115 with the main code (algorithm). In this project a source code for UART, LCD, ADC and ZigBee was developed and used along with the main load-cell WSN algorithm. To program the microcontroller WINAVR was used. Although inline assembly was possible, the programming was done strictly in C. Burning After coding and compiling the program must be burnt into the microcontroller. Here burning the machine language file into the microcontroller s program memory is called burning which is achieved with the dedicated programmer attached to the PC peripheral. PC s serial port has been used for this purpose. Robokits Programmer was been used for burning process. LOAD-CELL WSN ALGORITHM A proper step by step algorithm was developed and written in AVRStudio4 in embedded C and compiled successfully using WINAVR. The compiled code was burnt into Atmega 32 micro controller using ISP programmer. The Load-Cell WSN algorithm can be summarized in the following way using Embedded C platform. The algorithm can be summarized as shown below in a flowchart The received data V a is converted into digital value by Figure 6: Load WSN Algorithm The digital data V d is then converted into actual weight by (1) (2) RESULTS The module was successfully developed and tested in the laboratory assuming the required environmental conditions. The transmitter was able to transmit the data up to 200mts distance. The following table shows the applied weight, measured, voltage and the weight of the object obtained. The results are accurate with minor errors in reading. These can be said to be due to variable environmental conditions and equipment. The following figure shows the transmitter and the receiver of the module.
116 Nayeem Muddin Khan D, Gnl Ravi Teja, R Bhargava Krishna & Rajesh Singh Figure 7: Transmitter and Receiver Circuit CONCLUSIONS AND FUTURE SCOPE The module designed in this paper was tested for different loads and it was concluded that the output acquired was in compliance with the input with few errors which were due to the poor condition of the load cell sensor. The output of the module was verified with the output of the load cell trainer kit (Model No: ITB - 04CE) and found to be accurate. Such a module, built successfully can be used for many applications. The same technology can be used to monitor pressure, temperature, flow, level and different parameters which used in industries. The range can be increased from 200mts to 20km. REFERENCES 1. H. Karl and A. Willig, Protocols and Architectures for Wireless Sensor Networks, John Wiley and Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, England, 2005. 2. Using Wireless Sensor Network on Real-Time Remote Monitoring of the Load Cell for Landslide Yao-Ming Hone': Hsueh-Chun Lin2, and Yao-Chiang Kan3 1Department of Design for Sustainable Environment, MingDao University, Peetow, Changhua 52345, Taiwan 2Department of Health Risk Management, ChinaMedicalUniversity, Taichung 40402, Taiwan 3Department of Communications Engineering, Yuan' Ze University, Chung-Li, Taoyuan 32003, Taiwan. 3. J. F. Akyildiz, W. Su, Y. Sankarasubramaniam, and E. Cayirci, Computer Networks. 4. Pressure monitoring in wireless sensor network using Zigbee transceiver module Singh, R.; Mishra, S.; Joshi, P. Computer and Communication Technology (ICCCT), 2011. 5. Kavi K. Khedo, Rajiv Perseedoss and Avinash Mungur. Department of Computer Science and Engineering, University of Mauritius,Reduit,Mauritius. 6. Fei Lu, Guo-Hui Tian, ZigBee Based Wireless Sensor and Actor Network in Intelligent Space Oriented to Home Service Robot, School of Control Science and Engineering, Shandong University, Jinan, China, 2012