ES-U-2001-S
Installation Guide
Version 1.1
Document Reference No.: CP_000074 Clearance No.: CP#062
Copyright © Connective Peripherals Pte Ltd
7
3.3
Termination and Biasing Configuration
Inside the unit, there is a 7 x 3 header block. This allows jumpers to be fitted to enable Tx, Rx and
CTS 120 Ohm termination resistors and to enable the Tx and Rx 750 Ohm Biasing resistors.
Figure 3 – 7 x 3 Header Block to enable Termination & Biasing Resistors
You will need to open the upper case and set the jumpers as per the requirements of your application.
The jumpers control the following settings. Please refer to the notes on the following page before
setting the jumpers.
Jumper
Function
1-2 enable
Tx+/- Termination of 120 Ohm (see notes below table)
2-3 disable
4-5 enable
Pull-up Tx+ to VCC via 750 Ohm Bias resistor (see notes below table)
5-6 disable
7-8 enable
Pull-down Tx- to GND via 750 Ohm Bias resistor (see notes below table)
8-9 disable
10-11 enable
Rx+/- Termination of 120 Ohm (see notes below table)
11-12 disable
13-14 enable
Pull-up Rx+ to VCC via 750 Ohm Bias resistor (see notes below table)
14-15 disable
16-17 enable
Pull-down Rx- to GND via 750 Ohm Bias resistor (see notes below table)
17-18 disable
19-20 enable
CTS Termination of 120 Ohm (for RS422 mode) (see notes below table)
20-21 disable
Table 2 – Termination and Biasing Jumpers
Note on Termination:
For RS485 half-duplex, if termination is required, only Tx Termination should be enabled as the
Tx and Rx lines are linked. Enable Tx+/- termination (jumper 1-2) and disable Rx+/- termination
(jumper 11-12)
