COMT 366 Series

CyberResearch® Serial Communications

4.1 Termination of the Line

There are four user-selectable resistive terminating values which are implemented using switches A and B of the dipswitch. As the length of the transmission cable and the number of users increases, the chosen value becomes more critical to error-free operation. Typically, devices at the end of a long bus are terminated and units multi-dropped between the ends are not terminated. The cable used to connect devices off the long bus should be kept as short as possible. The value chosen should match the characteristic impedance of the twisted pair being used. The termination value can be selected using the following table

Switch

Termination Value

1

2

OHMS

Off

Off

None

On

Off

200

Off

On

120

On

On

75

6

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