| 摘要 |
The outputs of subscribers (1) connected to a bus are equipped with tristate circuits (6) which contain clamp diodes (19) between the bus lines (8) and the operating voltage terminals (10, 11). The operating voltage is fed to the tristate circuits (6) via a diode (14) and a resistor (21). A resistor (12) is disposed between one operating voltage terminal (11) and the control input (9) to set the high-impedance state. In the event of operating voltage failure, the tristate circuit (6) is switched to the high-impedance state by the potential on the bus lines (8). A capacitor (22), which supplies the tristate circuit (6) with operating potential and the control input of the tristate circuits with a reverse voltage when low potential occurs on all bus lines (8), is connected between the operating voltage terminals (11, 10). <IMAGE>
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