| 摘要 |
PURPOSE:To attain proper collision control if a D-channel loopback test request from a network and a D-channel communication from a terminal equipment are competed to each other by providing a D-channel collision control section, a selector and an AND gate to a network terminator. CONSTITUTION:Plural terminal equipments are connected from a network terminator connected to a subscriber line in a bus form and a terminal equipment and a network are communicated by using a D-channel signal via the network terminator to control data transmission/reception of data. In case of communication enable, a D-channel collision control section 11, a 1st selector SEL1, a 2nd selector SEL2 and an AND gate 12 are provided to a D-channel control section to control the transmission/reception of the D-channel between the terminal equipment and network constituting the network terminator in the communication system loop-back the D-channel to the E channel to the terminal equipment. Thus, whether or not the terminal equipment applies communication through the D-channel is checked and the test is conducted in idle state.
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