| 摘要 |
An input/output controller for an extension unit of a programmable logic controller (PLC). The input/output controller has a first port connected to the PLC and a second port connected to a terminal device of the extension unit. A memory is provided to save data received from the first port and the second port. A mode-selecting circuit of the input/output controller includes a plurality of preset operation modes, which determine the input or output type of the first and second port, data-transmitting format used by the first and second port, and data-saving format used in the memory. Thus, the PLC can receive data from the terminal device, or can transfer predetermined data to the terminal device through the input/output controller of the present invention.
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