Document Reference No.: ES_000086

ES-R-2x01B-M RS-232 to RS-422/RS-485 Converters Manual

Version 1.0

Clearance No.: ES

©2010 - 2011 EasySYNC Ltd.

8

Inside the converter, there is a 7x3 (21pin) header block which has jumpers to enable the Tx, Rx and

CTS 120 Ohm termination resistors, and the Tx and Rx 750 Ohm biasing resistors. Open the case and set

the jumpers as per the requirements of your application. The settings are detailed below.

Figure 3

Setting termination and biasing resistors

Jumper

Function

1-2

enable

2-3

disable

Tx± Termination of 120 Ohm.

This function should be enabled for RS485 Half-Duplex mode.

4-5

enable

5-6

disable

Pull-up Tx+ to VCC by 750 Ohm Bias resistor.

This function should be enabled to pull-up Tx+.

7-8

enable

8-9

disable

Pull-down Tx- to GND by 750 Ohm Bias resistor.

This function should be enabled to pull-down Tx-.

Rx± Termination of 120 Ohm.

This function should be enabled for RS-422 and RS485 Full-Duplex mode.

Pull-up Rx+ to VCC by 750 Ohm Bias resistor.

This function should be enabled to pull-up Rx+.

Pull-down Rx- to GND by 750 Ohm Bias resistor.

This function should be enabled to pull-down Rx-.

CTS Termination of 120 Ohm.

This function should be enabled for RS-422 mode.

Note: See section 4.1 for further information before setting termination and biasing

Table 3

Termination and Biasing configuration

21 20 19

3 2 1