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Chapter 3 Termination board wiring
Termination resistor placement for Comm5 links
Install one 105 Ω resistor across the communication link terminals of the device at the beginning of the daisy chain, which is typically a Tracker controller. Then install a second 105 Ω resistor across the communication terminals at the last UCM on each link. See Figure 17 on page 35 for an example of a link that begins with a Tracker controller. See Figure 18 on page 36 for an example of a link that does not begin with a Tracker controller.
Note:
If, after installation, the link is extended to add more UCMs, the resistor must be relocated to the new last UCM on the link.
IMPORTANT
For maximum performance of the Comm5 link, use the 105 Ω resistors that are included with the Tracker controller. If they are not available, as a second choice, use a 100 Ω, ¼ W, 5% tolerance resistor, or as a third choice, a 110 Ω, ¼ W, 5% tolerance resistor. Failure to comply may cause the controller to malfunction.
The resistor value can be determined by reading its color bands. Table 9 provide the resistor color coding.
Table 9. Resistor color band table
Tolerance | Color sequence |
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105 Ω ± 1% tolerance | Brown, black, green, brown |
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100 Ω ± 5% tolerance | Brown, black, brown, gold |
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110 Ω ± 5% tolerance | Brown, brown, brown, gold |
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If a repeater is used, each link of the configuration that is created by the repeater requires termination resistors (see “Requirements for repeaters on Comm5 communication links” on page 37).
Create a set of
34 |
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