Industrial Ethernet Ida Specification Communications Services

Industry Ethernet is the development trend in current control net, but it also has some questions, one of them is the specification of a standard application protocol for industrial automation. In the existing specifications, the Interface for Distributed Automation Specification (IDA) has the obvious specialty.In the article, the system's structure model and the realization steps are introduced briefly in the first. Then the communication services in the IDA specification are researched in detail. In the four IDA communication services, data distribution service can refresh the input and output data for the users' application function block, it is based on a preconfigured optimized publish/subscribe mechanism provided by the RTFS. Event notification service can inform the operator about the alarm status and trend data, it is based on the reliable publish/subscribe mechanism. Remote method invocation service is used to call the functions in other modules, it is based on the confirmed client/server mechanism. On-demand data exchange service adopts the MODBUS/TCP protocol to get the different parameters from PLC.In this article, the communication services of IDA are applied in the I/O module which has the core of Rabbit2000. The realization includes: the transmission of 6-channel analog inputs, 8-channel discrete inputs and the alarm status based on the data distribution service, the transmission of alarm limit based on the event notification service, the control of 8-channel discrete outputs based on remote method invocation service and the discovery of the applications in network. The 6-channel analog inputs also transmitted based on the on-demand data exchange service. The realization adopts the object oriented method, the data and behavior are encapsulated. This method hide the details of realization, the users only need configure the communication parameters to compose the system. And the software can be modified, expanded and maintained more easily.The practical development and realization prove that the communication services of IDA have some advantages, such as simple structure etc. And it can be accepted by the user and developer easily.