| 摘要 |
<p>PURPOSE: To immediately recognize signal abnormality with a circuit fault at a computer by providing two pairs of buffer circuits and gate circuits, comparing the outputs of respective gate circuits and adding the signal of that compared result to data to be sent to the computer as a redundant bit at the digital signal input circuit of a digital controller for transmitting a digital signal inputted from a plant to the computer. CONSTITUTION: A DI card 2 for transmitting the digital signal from a plant 6 to a computer 5 is provided with two pairs of buffer circuits from 11-11 to 11-1n and from 11-21 to 11-2n and gate circuits 12-1 and 12-2, comparator 17 for digitally comparing the output signals of respective gate circuits, and logic circuit 18 for adding a parity bit to the output signal of the gate circuit 12-1, adding the signal of the compared result as the redundant bit, encoding that signal and transmitting it to the computer 5.</p> |
