| 摘要 |
A programmable sequence controller is disclosed utilizing digital and analog inputs in order to generate digital output driver signals for the control of external systems or devices. The controller emulates mechanical sequence drums so that at any one time each of the simulated drums within the controller executes one of the addressable drum lines programmed within the drum. Each line of each simulated drum can be programmed to specify the energization or deenergization of any output driver as well as the energization or de-energization of any memory bit utilized by the controller in order to provide communication between drums. Each drum may also be programmed to have one or two sets of exit conditions, which if met, cause the controller to effectively rotate the drum to a specified drum line and execute this new drum line during the next scan of the controller. The controller can also sense emergency conditions and cause any or all of the drums to rotate to a specified line regardless of the drum line then being executed by the controller for each of the drums. An improved power-down, power-up circuitry insures an ordered and complete shutdown of the controller if any of a number of conditions exist, including utility AC failure and impending failure of several of the power supply voltages. Handshaking circuitry between the power supply and the remainder of the controller insures that the controller maintains memory validity for all types of shutdown situations, including momentary losses of any supply voltage. The programmable sequence controller includes a clock-calendar capable of continued operation during periods of extended power outages. The clock-calendar can be utilized in any drum line to form part of the control scheme. All programming of the simulated drum lines is performed through an interconnected data communication device such as a teletypewriter and utilizes a simple user-oriented language, with monitoring and diagnostic capability to facilitate debugging.
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