| 摘要 |
<p>PURPOSE:To make it possible to detect rapidly an abnormal state without deteriorating the data processing performance of a communication controller and also to perform cutting operation in a short time by providing a circuit which detects the abnormal state in parallel to synchronous test operation. CONSTITUTION:When the state of receiving circuit R changes from ''1'' to ''0'' at time t0 and the state of indication circuit I also changes from OFF to ON, an abnormal state of circuit cutting indication is considered to have occurred. Then, this state is immediately detected to change the state of control circuit C from ON to OFF, and the state of transmitting circuit T is also changed from ''1'' to ''0'' to complete response operation (t1-t0) of incoming disconnection in a short time (within 100ms). Namely, before a synchronous character or start flag is tested by synchronous test circuit 27, the generation of eight continuous bits of ''0'' is detected by ''0'' detection circuit 28 to send interruption signal INT to a main control part and a control program starts fixed corresponding operation, thereby detecting the abnormal state.</p> |
