TEXAS INSTRUMENTS INCORPORATED;TEXAS INSTRUMENTS JAPAN LIMITED
发明人:
KAMATH, Anant
申请号：
WO2018US31553
公开号：
WO2018208750(A1)
申请日:
2018.05.08
申请国别(地区):
世界知识产权组织国际局
年份:
2018
代理人:
摘要：
An optocoupler (350) is placed in series between a field ground pin (FGND) of digital input circuitry (300A, 300B) and a field ground (351) of an industrial controller. A capacitor (356A, 356B) to field ground (351) is provided for each digital input. A resistor (354A, 354B) is provided to the input pin (IN) of the digital input circuitry (300A, 300B). To detect a brokenwire, a test pulse (TEST PULSE) is provided to the optocoupler (350) connected in a ground path. This test pulse (TEST PULSE) isolates the digital input circuitry (300A, 300B) from field ground (351). As current is always being provided from the field when the wire is not broken, the capacitor (356A, 356B) connected between the input and ground charges. After the test pulse (TEST PULSE) has completed, the output signal (OUT) of the digital input circuitry (300 A, 300B) is examined. If the level indicates the input is high, the wire is not broken. However, if the output remains low indicating that the input is low, the wire has broken.
