| 摘要 |
<p>PURPOSE:To recognize interruption of a power supply by connecting a switch representing power on/off state in parallel with a communication line, turning on the switch at the state of interruption of the power supply to short-circuit the communication line, thereby detecting an unchanged signal level. CONSTITUTION:A loop is turned on/off between TDP' and TDM' in the reception operation at a terminal equipment A when a TR 4 of a terminal equipment B changes its level, the state is detected by a TR 2 of the terminal equipment A to cause a change in a signal level at an ACIA.RD point. When the power of the terminal equipment B is failed, a SW 1 is closed and the loop between the TDP' and TDM' is opened. A change in the signal level is not caused in the TR 2, the ACIA changes a status register into the state of RDRF=1 and FE=1 by software and power interruption of the terminal equipment B is recognized by the state of not being in the communication state. When the SW 1 is opened by application of power, the TR 2 detects a change in the signal level, and when a transmission code is received, the status register of the ACIA changes as FE=0 and the software recognizes power application of the terminal equipment B.</p> |
