Connecting to telephone networks wired in bus topologies - MicroScanner2
Telephone cables wired in a bus topology (Figure 1) connect the wall outlets in series. In this topology, you measure the length from the last outlet to the wiremap adapter.
If you connect to an outlet in the middle of the series, the tester reports a bridge tap. The length reported is the length to the outlet, which is the patch cord length. The tester cannot measure length past the outlet because reflections from the cables on either side interfere with measurements.
If you are unsure which outlet is the last in the bus, do the following:
If you connect to an outlet in the middle of the series, the tester reports a bridge tap. The length reported is the length to the outlet, which is the patch cord length. The tester cannot measure length past the outlet because reflections from the cables on either side interfere with measurements.
If you are unsure which outlet is the last in the bus, do the following:
- Connect the wiremap adapter or ID locator to the beginning of the bus at the distribution center.
- Connect the tester to an outlet and run the twisted pair cable test.
If the tester reports a bridge tap, move to another outlet. The last outlet will not show a bridge tap, and will show the length to the distribution center.
Caution
Do not use multiple far end adapters in star or bus topologies.
Doing so causes incorrect wiremap results. 
図 1. Connecting to a Telephone Network Wired in a Bus Topology
