Phonetics Annunciator Module SCADA 3000 - Manual (Page 9)

AM-9
Annunciator Module
10 B A B A
11 A A B A
12 B B A A
13 A B A A
14 B A A A
15 A A A A
Figure 5: Setting the Bus Address
Bus Termination
Located on each module is a jumper labeled BUS TERM. This jumper is used to terminate the
4-wire communications bus.
0
BUS TERM
IN OUT
Figure 6: Bus Termination jumper
Termination is required at the extreme ends of the communications network to minimize signal
reflections that would otherwise cause data communication errors. To activate the Bus Termina-
tion, move the jumper to the IN position. Note that this should only be activated if the module
is at the very end of the network. All other modules in between should have the termination set
to the OUT position. As a result, only 1 module should ever have the termination activated.
The diagram below illustrates proper termination of the communications bus.
In Out Out Out In
Main
Unit
Figure 7: Correct bus termination