| 摘要 |
A system for controlling operations of a process or of another system or apparatus which must perform its operations in precise time sequence. The control system also initiates the performance of successive cycles of such sequences of operations with the same precision of timing as the operations themselves. A timing generator which operates from or includes a constant frequency source produces pulses of constant periodicity which time the operations so that they occur in selected time sequence during each cycle, starting when a cycle is initiated. The timing of the operations and their duration may be preset for the process, apparatus or system to be controlled. A large timing range is provided to meet the needs of the particular process system or apparatus and to make adjustments as may be required in the field. The cycles of operation sequences may be selected in accordance with the mode of operation desired. A preset interval timer operated by the timing generator may be selected by the mode selector to initiate the cycles of operation at preset time intervals. Other apparatus which may be located remotely from the control system may initiate a cycle of operations. Control of the operations in response to external control signals such for example as represents the level of liquid or other materials being processed or monitored, may be used to control the duration of an operation and if the signal does not arrive, to terminate the cycle of operations and indicate a fault condition.
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