Bus Termination; Rmba-01 User's Manual - ABB RMBA-01 User Manual

Modbus adapter module

Table of Contents

Chapter 3 – Installation

Bus termination

3-4

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The built-in active bus termination must be switched on

if the RMBA-01 module is installed at the end of the

bus. Otherwise the bus termination must be switched

off. Bus termination prevents signal reflections from the

bus cable ends.

Bus termination OFF

Figure 3-4 Bus termination switch (S1)

Note: The built-in termination circuitry of the RMBA-01

is of the active type, so the module has to be powered

for the termination to work. If the module needs to be

switched off during operation of the network, the bus

can be terminated by connecting a 220 ohm, 1/4 W

resistor between the A and B lines.

Bus termination ON

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