Phonetics SCADA 3000 manual Bus Termination, Setting the Bus Address

			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.

BUS TERM

IN OUT 0

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.

Main

Unit

In	Out	Out	Out	In
	Figure 7: Correct bus termination

AM-9