A Communications Technology Research Of Devicenet Slave Node Based On Different Data Trigger Modes

As one of the international standards of fieldbus,DeviceNet has become focus of attention increasingly.Therefore,do some research on development of slave node based on DeviceNet is very pressing and necessary.After research the protocol specification of DeviceNet,this paper designs a DeviceNet fieldbus communication node which used the SJA1000,a type of separate CAN controller.On the basis of following the predefined master/slave connection set specification,the node can meet the input and output functions with either digital or analogue data type,and support both poll and bit-strobe I/O data trigger modes.First , this paper describes the research progress of devicenet home and abroad,content and significance of this paper,and specified the protocol specification of DeviceNet.Then give the detailed working principle of poll and bit-strobe which are the primary data trigger modes.After then,it designs the hardware circuit of commnication node.For the good portability and powerful functions of separate CAN controller,this paper gives a brief description of SJA1000 and other components firstly,then uses the SJA1000 CAN controller to complete the hardware development of DeviceNet communication node,also gives the detailed hardware circuit,and gets through the debugging.The software design of DeviceNet slave node is realized by C51 language.For more clear program structure and simplifying the debugging process,this paper edit the program of application layer based on objectification programming method.The program can realize the elementary functions such as initialization of SJA1000 and correlative parameters ,also the transceiving of CAN message,etc.Then,it can realize the duplicate MAC ID detection,configuration of connection instances,transceiving of explicit message,etc.After that,it considers the communication demand of both poll and bit-strobe modes,and gives the detailed program code.For testing the function of the slve node which this paper have developed,it builds a test platform for DeviceNet slave node,and also tests the developed node.By analyzing the experimental data in detail,it has proved that the node can act according the demand of DeviceNet specifications completely and realize the communication function of intelligent slave node in different data trigger modes.