Dataforth SCM9B-D192 Series Руководство пользователя - Страница 6

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6 SCM9B-D192 USERS MANUAL

ground. The biasing resistors and are normally positioned at the HOST

end of the cable. The RS-485 standard also requires two resistors across

the data lines for proper termination. Two 220Ω resistors should be

connected between the DATA and DATA* lines. The resistors should be

placed at each end of the RS-485 cable. Please refer to Figure 2 for a

typical RS-485 system application.

The SCM9B-D192 contains the biasing and termination resistors

necessary to interface any equipment on an RS-485 network. These

resistors are jumper-selectable making it easier to interface the SCM9B-

D192 to other pieces of equipment that may or may not contain the

biasing and/or termination resistors.

RS-485 TERMINATION & BIASING SETTINGS

Proper termination and biasing of any RS-485 based system can be

performed by properly enabling the correct resistors inside each SCM9B-

D192. Figures 2.0 shows the location of the jumpers on the printed

circuit board. The jumpers are shown in their factory set locations to

enable the selected resistors. Insert or remove the jumpers as required to

properly terminate any RS-485 system.

FIGURE 2. SCM9B-D192 jumper locations.