| For the advantages that the fieldbus control system has, such as using less wires, low cost, flexible, reliable, fieldbus occupies an important position in the industrial process control systems. The DeviceNet, since been advanced, has been extensive development for its unique advantages. In recent years, the development efforts of domestic manufacturers for DeviceNet slaves continue to enhance, the types of equipment and the number are growing. However, because of the limited skills and experience and other factors, the proportion of passing ODVA certification one-time is very low, the means of testing of the communication functions and performance are very different for different equipment manufacturers. Therefore, the development of a communication testing system for the DeviceNet slave is of important significance.In order to clarify the DeviceNet conformance test requirements of the test system, the paper firstly analyzes the DeviceNet protocol, and studies the software conformance testing of conformance test, makes a detailed description of the contents and indices of the object model testing and response time testing. Then, the conformance test program is given from the message level, based on the results of analysis. In order to solve the communication function problems of the DeviceNet slave, the general testing program which is based on the idea of black-box testing is proposed. In order to achieve the purpose of communication performance test, auxiliary test slaves self-developed are introduced to simulate the fault status and different network load factor needed in the testing.The communication test system of the DeviceNet slave is designed, according to the test programs designed before. The selection of DeviceNet interface card and I/O control card is described. The necessary hardware and software of the auxiliary test slaves device are designed, and the main circuits of the hardware and main program modules of the software are described in detail, the hardware schematic and program flow charts are also given in the paper.At last, the PC software is designed according to the idea of structured and modular. Taking the self-developed DeviceNet slave as the measured object, the actual operation and test sample of the test system is given. The results shows that the developed communication test system of the DeviceNet slave has reached the requirements of designing, and has the features of full-featured, configuration flexibility, versatility. The test system could be a reference to the fieldbus products testing. |
