| 摘要 |
A method of communication between a programmable industrial controller and a user system which are interconnected via an interface including first, second, third, fourth, and fifth storage means, the controller including a control unit connected to a peripherals bus over which data and addresses travel, each data item being associated with an address. According to the invention the method consists initially in triggering communications cycles synchronizing with the operating cycles of the controller, and secondly, during a communications cycle, either in performing the following operations in parallel: 1) storing each data item emitted by the user system in the first storage means, or in the second storage means, and authorizing the controller to read from the second storage means, or from the first storage means, depending on whether, during the preceding communications cycle, data emitted by the user system has been stored in the second storage means or in the first storage means, and the controller has been authorized to read from the first storage means or from the second storage means; 2) storing each data item travelling over the peripherals bus in the third storage means at the address associated therewith after storing said address and said data in the fourth storage means, each time said data item is different from the data contained at said address in the third storage means; and 3) communicating the information contained in the fifth storage means to the user system on request therefrom; or else in transferring the information contained in the fourth storage means to the fifth storage means. The invention also relates to the interface for implementing the method. The invention is applicable to simulating the input/output cards of an industrial controller.
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