| 摘要 |
PURPOSE:To obtain the communication line test circuit whithout increasing the communication path constitution, by taking the least signification bit of the information word as the parity check bit. CONSTITUTION:The transmission signal from the transmission side subscribers 19, 20 is fed to the reception side subscribers 21, 22 via the parity insertion circuits 15, 16 and communication line 13. The central control unit 14 stops the operation of the parity insertion circuits 15, 16 at non-test of communication line, and the transmission signal of the transmission subscribers 19, 20 is delivered to the communication line as it is. At the test of communication line, the parity insertion circits 15, 16 deliver the least significant bit of the transmission signal to the communication line 13 as the parity bit to the most significant bit. The parity error detection circuits 17, 18 detect the code error caused on the communication line 13 with the above mentioned parity bit. |
