| 摘要 |
PURPOSE:To monitor the operating state of a branch/insert circuit in on line state without giving effect on substantial data communication by inputting a PN pattern to an idle input of the branch/insert circuit and using its output for the collation test. CONSTITUTION:A branch/insert circuit is provided, which has plural inputs and plural outputs corresponding one to one to the plural inputs. A data IN inputted from a transmission line is inputted to the branch/insert circuit 1, in which branch/insert control is implemented and the result is outputted as a data output OUT. Moreover, a PN patter S1 outputted from a PN pattern generating circuit 2 is inputted to an idle input for monitoring of the branch/ insert circuit 1 and its output S2 is inputted to a PN pattern collation circuit 3, and its monitor output MON is used for collation test. That is, the PN pattern and the PN pattern outputted from the branch/insert circuit 1 are collated by the collation circuit 3. |
