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-232 mode, or RS-422, or RS-485 mode as per the requirements of your application.

 

 

The Mode Block Configuration Settings are listed as follows:

 

 

SW (External DIP Switch) for Mode Setting

 

 

 

   Operation  Mode

 S1

 S2

 S3

 S4

RS-232

Standard RS-232 Mode

 

OFF

 ON

 ON 

 ON 

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

 

 

 

JP1 for Termination and Biasing Option Configuration

 

Inside the unit, there are eight 2 x 7 (14 pin) header blocks which are jumpered to enable Tx, 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

 

Tx Termination of 120 Ohm.

This jumper should always be populated for RS-485 mode.

3-4

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

This jumper should be populated for pull-up Tx+.

5-6

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

This jumper should be populated for pull-down Tx- .

7-8

Rx Termination of 120 Ohm.

This jumper should always be populated for RS-422 mode.

9-10

 

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

This jumper should be populated for pull-up Rx+

11-12

 

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

This jumper should be populated for pull-down Rx- .

13-14

 

CTS Termination of 120 Ohm.

This jumper should always 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.

 

 

JP2 : Enable the +5V 150mA Power for External Device

 

The USB-COMi-M provides a unique feature of supplying power output of 5V/150mA through Pin-5 of terminal block to the serial device requiring power. By default, this feature is disabled. 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 Terminal Block Pin-5 to support a 5V 150mA power for external device requiring power

 OFF

Disable the 5V 150mA power (Default)

 

 

RS-232/422/485 Pin-outs & Signal Wiring

 

 

 

 

RS-232 Signal Pin-outs of DB-9 Male (CN2)

 

Pin 1

DCD

Pin 2

RxD

Pin 3

TxD

Pin 4

DTR

Pin 5

GND

Pin 6

DSR

Pin 7

RTS

Pin 8

CTS

Pin 9

RI

 

RS-232 Signal Pin-outs of Terminal Block (TB1)

 

Pin 1

DCD

Pin 2

RxD

Pin 3

TxD

Pin 4

DTR

Pin 5

+5V

Pin 6

                                    GND

 

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

+5V

Pin 6

GND

 

 

RS-422 Signal Wiring  

 

    l    Point-to-Point 4 Wire Full Duplex

 

    l    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

+5V

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

+5V

Pin 6

GND

 

 

 

RS-485 Signal Wiring

 

    l    Point-to-Point 4 Wire Full Duplex

 

    l    Multidrop RS-485 2-Wire Half-duplex