Impulse 2113 - Manual (Page 11)

RS-422/485 Products
Items# 2112, 2212
Dip switches on SeaLINK USB RS-422/485 serial adapters provide the ability to
communicate with RS-422 or RS-485 devices. These switches are also used to set
RS-485 enable modes and termination options. Single port models have a single
eight-position dip switch. Two port models have a pair of eight-position dip switches
allowing each port to be individually configured. All configuration changes can be
made without opening the enclosure.
Dip Switches
Switch ON OFF
8 2 Wire – 4 Wire –
7 2 Wire + 4 Wire +
6 RD 1K PU –
5 RD 1K PD –
4 120Ω Termination –
3 Echo Off Echo On
2 RS-485 RS-422
1 RS-422/485 –
Switch Function
8 RS-485 Option, OFF for RS-422
ON: Connects TX– and RX– for two-wire operation
OFF: Separates TX– and RX– for four-wire operation
7 RS-485 Option, OFF for RS-422
ON: Connects TX+ and RX+ for two-wire operation
OFF: Separates TX+ and RX+ for four-wire operation
6 RS-485 Option, OFF for RS-422
ON: Adds a 1K Ω pull-up resistor to RX+
OFF: Leaves RX+ floating
5 RS-485 Option, OFF for RS-422
ON: Adds a 1K Ω pull-down resistor to RX–
OFF: Leaves RX– floating
4 RS-422, RS-485 Option
ON: Adds a 120Ω termination resistor between RX+ and RX–
OFF: No line termination
3 Two-Wire RS-485 Option, OFF for RS-422, Four-Wire RS-485
ON: ECHO Off. The receiver is disabled when the transmitter is enabled.
In a two-wire setup the receiver will not echo back transmitted data
OFF: ECHO On. The receiver is always enabled. In a two-wire setup the
receiver will echo back all transmitted data
2 Mode Selection
ON: RS-485 mode. The transmitter lines TX+ and TX– are switched to
high impedance when the device is not actively transmitting data
OFF: RS-422 mode. The transmitter lines TX+ and TX– are always driven
1 Mode Selection
ON: RS-422, RS-485 mode
OFF: Must be ‘ON’
© Sealevel Systems, Inc. - 9 - SeaLINK DIN Rail USB Serial Manual