Design And Implementation Of The Intelligent Communication Adapter For The Boiler Assistant Equipment Based On Devicenet

With the development of modern industry, the need for electric power is increasing day by day,and the shortage of electric power is becoming seriously. The electric power industry is coming into the period of greater electric power network, greater power generation set and greater automation. All these require that the power plant must have more stable and efficient process control system with the powerful function for real-time monitoring and control. At present, the extent of manufacture process automation in power plant is comparatively high, but the physical distance of control system for the boiler assistant equipment is so far that the components of the system are more independently and lack of information interchanging. It brings great difficulty to the management in the plant level. So it is pressing for a united control system to monitor all parts of the system. Presently, the power plant usually make use of the distributed control system, called DCS. But for the limits of its characteristic and the demand of the system, when DCS is applied to control system for the boiler assistant equipment, it exists a lot of the shortcomings, such as high cost(most of the equipments need to be imported),the bad interchanging speciality among the equipments from different producers ,and the cockamamie control process.Aiming at the engineering background above, based on the project of"The preparation to construct the lab platform for the boiler assistant equipment's control system in power plant based on the Filedbus Control System"from the National Development and Reform Commission, and on the basis of deep research on the DeviceNet protocol, a control system for the boiler assistant equipment based on the Rockwell Netlink network and DeviceNet fieldbus is developed according to the detailed requirements of the demand for the boiler assistant equipment's control system. Also the key technology of the control system is researched, and a kind of DeviceNet slave device intelligent communication adapter, which has an independent knowledge property right, is impoldered.The main content of the paper is :The DeviceNet fieldbus protocol is studied deeply. Combining with the practical demand for boiler assistant equipment's control system in power plant, a control system for the boiler assistant equipment based on the Rockwell Netlink network and DeviceNet fieldbus is developed. According to the detailed requirements of the system's structure and principle, the impoldering of the DeviceNet slave device intelligent communication adapter is decided to be the key technology of the system. Two technique schemes for the communication adapter are brought forward,including using protocol conversion chip and the hardware and software design of the embedded system.The DeviceNet slave device communication adapter based on Anybus-IC is impoldered. On the aspect of hardware design, the expansion on the circuit of SSC,SCI,MIF interface and DeviceNet network interface is fulfilled on the basis of Anybus-IC module; On the aspect of software design, the parameter's setting and initialization of Anybus-IC module is carried through, and the establishment of Anybus-IC module's application parameters based on Modbus protocol is accomplished. With the singlechip's control program, the DeviceNet application layer protocol based on the Modbus protocol is fulfilled, and the correctness of the protocol's fulfillation is validated by the communication experiment between the Anybus-IC and singlechip.The DeviceNet slave device communication adapter based on the embedded system is impoldered. On the aspect of hardware design, the low-cost CAN bus communication scheme of combining STC89C58 with SJA1000 and 82C250 is fulfilled, and the DeviceNet network interface and popular functional module such as temperature collecting and valve interface control are expanded; On the aspect of software design, the CAN bus communication program, the DeviceNet application layer protocol program and the expanded functional module's driver program are written. Also the DeviceNet device profiles are accomplished, and the Electronic Data Sheet of the corresponding device is written.The DeviceNet slave device communication adapter is put to use in the experiment platform based on the Rockwell three-ply network. Through the communication experiment between the communication adapter and other DeviceNet devices in the same network, the correctness of the DeviceNet protocol's fulfillation is validated under the consistency testing in the lab. The experiment's result shows that the DeviceNet slave device communication adapter is reliable and easy-operational, and realizes the connection and the basic communication function between the intelligent devices on spot and DeviceNet network , and meets with the design requirements of the system.