| 摘要 |
<p>PROGRAMMABLE CONTROLLER A programmable system controller stores in memory a sequence of program words directly simulating a planar ladder diagram characterizing the desired operation of a controlled system. The ladder diagram is a set of n rungby-m column arrays of contacts interconnected with particular controlled devices of the system. The program words are read out of the memory in a sequence to directly represent the ladder diagram on a rung-by-rung basis for each column. The controller includes an interface unit coupled to a set of input switches for providing switch signals that are indicative of the operating status of the machine. A data processing unit is provided with an accumulator having a plurality of at least n storage units respectively corresponding to each rung of the ladder diagram. In response to the program words and to the switch signals, the accumulator sequentially determines the states of the storage units according to whether the switch signals are indicative that a particular rung of one column of the ladder diagram can contribute towards operating the controlled device as it is connected in the ladder diagram. After the plurality of storage units have been conditioned according to the rungs in one column, the next column of the ladder diagram is considered for conditioning the storage units. After all columns of the ladder diagram have been considered, a preselected one of the plurality of storage units contains an output signal indicative of whether the controlled device should be operated. 1.</p> |
