Network Design Considerations
2-19
TIWAY 1 Ti505 NIM User Manual
2.4.5
Terminating the Local Line
The TIWAY I Local Line is designed to operate with shielded, twisted-pair cable which
has a characteristic impedance of 124 ohms. In all configurations, the Local Line must be
properly terminated at both ends of the trunk to prevent an impedance mismatch which
could result in signal reflections on the line. Termination is required regardless of the
number or type of devices attached to the network.
NOTE
In the special case of a PM550 using a CIM as its interface to the net-
work, see Appendix A for detailed line biasing and termination instruc-
tions, which vary from those listed here.
Termination of the Local Line must be at the tap housings at the extreme ends of the net-
work spine, and is accomplished as follows:
1. The factory-installed termination resistors in the tap housing (see
Figure 5) are left in place in the tap housing which is to be used to terminate the
Local Line.
2. If the termination resistors are used and the attached TIWAY I device has a Bias
Switch, the Bias Switch should be set to the ON position.
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