| 摘要 |
PROBLEM TO BE SOLVED: To detect failure in an upper-level system by performing the arithmetic processing of physical quantity measurement output by a program, and stopping a pulse and fixing an output voltage when the output has deviated from a specific bandwidth. SOLUTION: The output voltage of a physical quantity detection element 1 which is composed of a bridge circuit consisting of resistors 3-6 changing resistance according to the change in measurement physical quantity is digitized by an A/D converter 8, and the middle voltage between the physical quantity detection element 1 and a resistor 2 is digitized by an A/D converter 7, and are subjected to arithmetic processing by a digital arithmetic unit 9, thus correcting an output voltage. The result is converted to analog by a D/A converter 10 and is outputted by an output circuit 12. When the physical quantity detection element 1 fails, the voltages of the A/D converters 7 and 8 extremely change. Therefore, a specific bandwidth is set to the measurement voltages of the A/D converters 7 and 8. When the measurement voltages deviate from the bandwidth over a specific time, it is regarded as failure, and the output of a pulse generator 11 is stopped, an output circuit 12 is stopped, and an output voltage is fixed to a power supply voltage or a ground voltage. |
