| 摘要 |
During the use of process equipment it is necessary to position control valves, change analog set-point signals for process controllers, move thermocouples to specific positions in thermowells, etc. A computer control system for these operations utilizes binary information on three sets of bits of a bus and an execute signal on another bit provided by a computer, usually at a remote area, to select the device of the equipment to be changed and to make the change. The system includes: an information interface card; a number of actuator module cards; decoder/demultiplexer means; and device select means. The interface card is connectable to first and second sets of bits of a bus that is connectable to additional systems. The device select means is connected to a third set of bits of the bus. The binary information to the device select means results in a signal only at one of its outputs, each output being connected to a different system. For the computer control system that output is connected to the input of first inverter means on the interface card. Second inverter means on the interface card is connectable to that another bit of the bus to receive the execute pulse to initiate the operation of the system, if selected by the device selector means. First and second gate means on the card have for each a number of gates with first and second inputs and an output. Means connected to these first inputs of the first and second gate means are connectable to different bits of the first and second sets, respectively, of bits of the bus. The second inputs of the first and second gate means are connected to the output of the first inverter means to open the gates when that inverter means is provided the device select signal. The inputs of the decoder/demultiplexer are connected to the outputs of the gates of the second gate means. Each actuator module card includes: storage buffer means having inputs corresponding in number to the number of gates of the first gate means, a corresponding number of outputs, and an additional input to receive a load signal to provide at those outputs retained binary information corresponding to the signals at the outputs of the gates of the first gate means at the completion of the load signal; means responsive to binary information at the outputs of the storage buffer means to provide at least one signal to change the operation of a device of the process equipment; a gate; and additional inverter means having an input and having its output connected to an input of the gate, while the output of the gate is connected to the load input of the storage buffer means. Another input of that gate on each module card is connected to the output of the second inverter means on the interface card to provide a load signal to the storage buffer means, when the additional inverter means of that card is signalled by the decoder/demultiplexer means to signal the means to change the device of the process equipment. The additional inverter means have their inputs connected to different outputs of the decoder/demultiplexer means.
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