USB to Serial Converters Manual
Version 2.0
Document Reference No.: CP_000032 Clearance No.: CP#022
Copyright © Connective Peripherals Pte Ltd
28
5.4
ES-U-2xxx-
M with 4
DIP
Switches
This section applies to the following adapters:
•
ES-U-2104-M
See the General Notes and Warnings on page 23 before changing settings or opening the cover.
The DIP switches should be set to select the correct serial mode before connecting the converter
to your RS-422/RS-485 serial bus.
DIP Switch Settings
On the outside of the unit, there are four DIP switches, which are used to select the required serial mode
(RS-422 or RS-485).
Operation Mode
S1
S2
S3
S4
RS-422
4 Wire with handshaking
ON
ON
OFF
OFF
RS-485
Full Duplex (4 wire)
ON
OFF
OFF
OFF
Half Duplex (2 wire) with Echo
OFF
OFF
OFF
ON
Half Duplex (2 wire) without Echo
OFF
OFF
ON
ON
Table 6 - RS-422 & RS-485 Mode Configuration
Switch S4 selects 120R termination of TxD. It is normally enabled for half-duplex RS-485 modes but may
not be required if both ends of your network are already terminated.
Jumper Settings
Inside the unit, there is a 6x2 (12 pin) header block for each serial port. Jumpers are used to select features
such as 120 Ohm termination on Rx and CTS, and 750 Ohm biasing resistors on Tx and Rx. You will need
to open up the cover and set the jumpers as per the requirements of your application.
Jumper
Function
1 - 2
Pull-up Tx+ to VCC by 750 Ohm Bias resistor. This jumper should be populated to
enable pull-up of Tx+
3 - 4
Pull-down Tx- to GND by 750 Ohm Bias resistor This jumper should be populate to
enable pull-down of Tx-
