Hardware Setting & Mode Configuration

Outside the unit, there is one 4-pin DIP switch which is set to select the mode of operation. You will need to set the switch settings to RS-422, or RS-485 mode as per the requirements of your application.

After the setting of DIP switch, you then plug the adapter to USB port to start driver installation. The Mode Block Configuration Settings are listed as follows

 

SW (External DIP Switch)
  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
Note
Half Duplex (2 wire) - without Echo
OFF

OFF
ON ON
Note

 

Note : In the most common situation , an 120 Ohm termination resistor of TxD (S4 is ON ) is required in RS485 Half Duplex configuration. Otherwise it is rarely used.

 

JP1 for Termination and Biasing Option Configuration

Inside the unit, there is one 2 x 6 (12 pin) header blocks which are jumpered to enable Rx, CTS 120 Ohm termination resistors and Tx, Rx 750 Ohm BIASing resistor.   You will need to open up the metal case and set the jumper setting for RS-422 mode or RS-485 mode as per the requirements of your application.

 

Settings are listed as follows:

Jumper Function
1-2 Pull-up Tx+ to VCC by 750 Ohm Bias resistor. This jumper should be populated for pull-up Tx+.
3-4 Pull-down Tx- to GND by 750 Ohm Bias resistor. This jumper should be populated for pull-down Tx- .
5-6 Rx Termination of 120 Ohm. This jumper should always be populated for RS-422 mode.
7-8 Pull-up Rx+ to VCC by 750 Ohm Bias resistor. This jumper should be populated for pull-up Rx+
9-10 Pull-down Rx- to GND by 750 Ohm Bias resistor.This jumper should be populated for pull-down Rx- .
11-12 CTS Termination of 120 Ohm. This jumper should be populated for RS-422 mode.

 

Note : Sometimes, when operating in RS-422 or RS-485, it is necessary to configure termination and biasing of the data transmission lines. Generally this must be done in the cabling, since this depends on the installation of connections. Before applying the option, check your cable specification for proper impedance matching.

RS-422/485 Pin-outs & Signal Wiring

RS-422/485 Pin-outs & Signal Wiring

RS-422 Signal Pin-outs of DB-9 Male (CN2)

 

Pin 1 Tx- (A)
Pin 2 Tx+(B)
Pin 3 Rx+(B)
Pin 4 Rx- (A)
Pin 5 GND
Pin 6 RTS- (A)
Pin 7 RTS+(B)
Pin 8 CTS+(B)
Pin 9 CTS- (A)

 

RS-422 Signal Pin-outs of Terminal Block (TB1)

 

Pin 1 Tx- (A)
Pin 2 Tx+(B)
Pin 3 Rx+(B)
Pin 4 Rx-(A)
Pin 5 GND
Pin 6 GND

 

RS-422 Signal Wiring

 

Point-to-Point 4-Wire Full Duplex

 

 

RS-422 with Handshaking

 


RS-485 4-Wire (Full duplex) Signal Pin-outs of DB-9 Male (CN2)

 

Pin 1 Tx- (A)
Pin 2 Tx+(B)
Pin 3 Rx+(B)
Pin 4 Rx-(A)
Pin 5 GND

 

RS-485 4-Wire (Full duplex) Signal Pin-outs of Terminal Block (TB1)

 

Pin 1 Tx- (A)
Pin 2 Tx+(B)
Pin 3 Rx+(B)
Pin 4 Rx-(A)
Pin 5 GND
Pin 6 GND

 

RS-485 2-Wire (Half duplex) Signal Pin-outs of DB-9 Male (CN2)

 

Pin 1 Data- (A)
Pin 2 Data+(B)
Pin 5 GND  

 

RS-485 2-Wire (Half duplex) Signal Pin-outs of Terminal Block (TB1)

 

Pin 1 Data- (A)
Pin 2 Data+(B)
Pin 5 GND
Pin 6 GND

 

RS-485 Signal Wiring

 

Point-to-Point 4-Wire Full Duplex
 
Multidrop RS-485 2-Wire Half-duplex