Design And Implementation Of Multi-channel Temperature Monitoring And Early Warning And Control System

Temperature is one of the most common parameters of the industrial automation field.The temperature detection elements present on the market would be too numerous to enumerate the production level, measurement accuracy, are also constantly improve.High accuracy, multi-channel temperature detection equipment, the price is expensive, the cost is very high.The purpose of this system is to reduce the cost of temperature measurement instruments and improve the detection accuracy of the system.Using conventional temperature sensor and PLC system with high performance and stability monitoring the temperature is What exactly we want to achieve.The master of engineering thesis based on PLC and PT100,Design and implementation the multi- temperature monitoring and early warning system. In this thesis the nonlinear feature of PT100 is briefly analyzed.The influence of two wire system, three wire system and four wire system on the measurement results is summarized and determine the temperature data collected by PT100.The integrated amplifier with the simple external circuit and the good performance of the instrument amplifier as the temperature acquisition circuit is used.PLC is used for controlling the core of anti-interference.Output linear control signal through nonlinear correction algorithm,The simple D/A circuit is designed.Design of communication function interface and protocol.The system has the functions of communication, display, alarming and driving control,achieve temperature monitoring, display,When the alarm is carried out in the abnormal range, the starting and stopping state of the device is controlled by the control circuit, and can be protected.In the process of system design,the development of the WINCC programming software and HMI STEP7 of the SIEMENS company.By the STEP7 software, including the function of an automation project from the beginning of the implementation of the hardware configuration and software programming, communication and so on each stage, with is simple and intuitive, easy to modify and flexible programming features. HMI development tool for the selection of SIEMENS WinCC. WinCC is the first process monitoring system using the latest 32 bit technology, with good openness and flexibility. WinCC can run in the Windows Microsoft system, has become the industry’s mainstream benchmarking products. The system uses the programming software and HMI software to ensure the system compatible and stable.After a period of debugging, the control system can correctly display the temperature change, when the temperature is outside the set range, will trigger the sound and light alarm. At the same time according to the abnormal temperature, control the site equipment, to prevent damage to equipment. In addition when the system appears the hardware failure or software failure, can call the STEP7 software interrupt block, will not cause PLC system downtime.