USB to Serial Converters Manual
Version 2.1
Document Reference No.: CP_000032 Clearance No.: CP#022
Copyright © Connective Peripherals Pte Ltd
17
RS-422
4 Wire with handshaking
ON
ON
ON
ON
RS-485
Full Duplex (4 wire)
ON
OFF
ON
ON
Half Duplex (2 wire) with Echo
ON
OFF
OFF
ON
Half Duplex (2 wire) without Echo
ON
OFF
OFF
OFF
Table 8 - RS-232, RS-422 & RS-485 Mode Configuration
Jumper Settings
Inside the unit, there is a 7x2 (14 pin) header block for each serial port. Jumpers are used to select
features such as 120 Ohm termination on Tx, Rx and CTS, and 750 Ohm biasing resistors on Tx and Rx.
You will need to open the cover and set the jumpers as per the requirements of your application.
Jumper
Function
1 - 2
Enable Tx+/- Termination with 120 Ohm (see notes below table)
3 - 4
Enable Tx Bias - Pull-up Tx+ to VCC by 750 Ohm Bias resistor (see notes below table)
5 - 6
Enable Tx Bias - Pull-down Tx- to GND by 750 Ohm Bias resistor (see notes below table)
7 - 8
Enable Rx+/- Termination with 120 Ohm (see notes below table)
9 - 10
Enable Rx Bias - Pull-up Rx+ to VCC by 750 Ohm Bias resistor (see notes below table)
11 - 12
Enable Rx Bias - Pull-down Rx- to GND by 750 Ohm Bias resistor (see notes below table)
13 - 14
Enable CTS Termination with 120 Ohm (populate for RS422 mode if termination is
required)
Table 9 - Jumpers to select Termination and Biasing
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 (leave jumper
7-8 open)
For RS485 full-duplex and RS422, termination can be enabled/disabled for Tx+/- and Rx+/- pairs
independently using the jumpers as required. See the notes on Termination in section 4.1 before setting
these options
Note on Biasing:
For RS485 half-duplex, if biasing is required, enable Tx+/- biasing only (jumper 3-4 and 5-6) and disable
Rx+/- biasing (leave jumper 9-10 and 11-12 open)
For RS485 full-duplex and RS422, biasing can be enabled/disabled for Tx+/- and Rx+/- pairs
independently as required. See the notes on Biasing in section 4.1 before setting these options
5V Power Enable Jumper (ES-U-3001-MB and ES-U-2101-MB)
The ES-U-3001-MB and ES-U-2101-MB can supply 5V (at up to 150mA) through Pin 5 of the terminal
block to allow external devices to be powered. To enable the power, you need to open the metal case and
set the jumper (JP2) to the position of
“ON”.
Jumper
Function
ON
Enable the 5V 150mA output on pin 5 of the Terminal Block to provide
power for external devices
OFF
Disable the 5V 150mA power (Default)
Table 10 - Jumper to select 5V output
RS232 Pin-Out (ES-U-2101-MB)
The ES-U-2101-MB has only a subset of the signals on the DB-9 connector to provide TxD, RxD, RTS,
CTS and GND. The pinout can be found in Table 12.
