Free Topology Restrictions; Bus Topology Networks; Bus Topology Restrictions; Figure 18. Combining Network Segments With A Repeater - McQuay MicroTech II Installation Manual

Figure 18. Combining Network Segments with a Repeater

Termination

Free Topology Restrictions

Although free topology wiring is very flexible, there are restrictions to the number of nodes on a segment, the maximum
bus length, and the wire size.
1. The maximum number of nodes per segment is 64.
2. The maximum total bus length depends on the wire size:
Wire Size Maximum Node-to-Node Length
24 AWG 820 ft (250 m)
22 AWG 1312 ft (400 m)
16 AWG 1640 ft (500 m)
The longest cable path between any possible pair of nodes on a segment must not exceed the maximum node-to-node
distance. If two or more paths exist between a pair of nodes (e.g., a loop topology), the longest path should be
considered. Note that in a bus topology, the longest node-to-node distance is equal to the total cable length. The total
length of all cable in a segment must not exceed the maximum total cable length.
3. One termination is required in each segment. It may be located anywhere along the segment.

Bus Topology Networks

You can extend the maximum total cable length of a network without using a repeater by using a bus network topology (see
Figure 19). The trade-offs are that 1) this network topology must be rigorously followed during the installation and
subsequent retrofits and 2) two terminations must be installed at the ends of the bus for proper transmission performance.
Note: Limitations to wire lengths apply and must be observed.

Figure 19. Bus Network Topology

Bus Topology Restrictions

The restrictions on bus topology are as follows:
1. The maximum number of nodes per segment is 64.
2. The maximum total bus length depends on the wire size:
Wire Size Maximum Cable Length
24 AWG 2952 ft (900 m)
22 AWG 4590 ft (1400 m)
16 AWG 8855 ft (2700 m)
3. The maximum stub length is 9.8-ft (3 m).
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Maximum Cable Length
1476 ft (450 m)
1640 ft (500 m)
1640 ft (500 m)
Termination
Termination
Termination
IM 781-2