Research And Implementation Of Device-independent Mechanism Based On CORBA Service For Open Architecture Controller

As modern manufacturing develops from mass single variety to mass custom-made direction, controller must rapidly adapt to the change of outer market environment by inner adjustment. This flexible manufacturing pattern requires the construction of Open Architecture Controller. Considering controller communicates with massive heterogeneous devices frequently and OAC needs to be device-independent, the paper focuses on the device-independent mechanism of OAC.This paper proposes two kinds of device-independent mechanism: CORBA Notification Service and Logical Device. The multi-to-multi loose-coupling communication manner, supplied by the NS, can alleviate tight coupling between users and devices; Because of accessing devices directly by device drivers, most traditional control systems have to make corresponding alteration when devices alter, while controller based on logical device mechanism could still be used without any alteration. RTCK is a design of real-time middleware frame in RTLinux real-time kernel.According to NS specification, a Notification Service architecture based on RTCK is presented. Based on this architecture, RTCK Notification Service is designed and implemented in RTLinux kernel space, supplying functionalities of communicating among objects, filtering and publish&subcribe-ing. An interface between user space and kernel space is also given, in order to send event to HMI. To ensure the performance of RTCK, a priority queue is utilized and the Leader/Followers concurrent model is adopted to realize Event Dispatching Thread (EDT) in the event channel.Some tests are executed to verify the effectiveness of designed system.About Logical Device mechanism, a series of device interfaces are given after abstraction of common devices in control area. Finally, an application scenario is given to show the open feature brought by Logical Device mechanism.