Datasheet
p/n 7207r4 485DRCI-0812ds page 4/5
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PRODUCT INFORMATION B&B ELECTRONICS
RS-485 4-Wire
(Full Duplex)
1. Loosen the screws to open the TB lead clamps for the
A, B, C, D, and E terminals.
2. Insert the RS-485 4-Wire signal leads. The terminal
board accepts 28 to 14 AWG wire.
3. Tighten the screws to close the TB lead clamps.
Ensure the clamps hold the leads securely. However,
do not over tighten. For Class 1 DIV 2 installations,
ensure the wiring is in accordance with the special
precautions and the specification table.
4. Configure the DIP Switch on the bottom of the
converter for RS-485 2-Wire operation (see above).
X. ON = Termination IN
OFF=Termination OUT
Y. ON=TX Bias IN
OFF=TX Bias OUT
Z. ON=RX Bias IN
OFF=RX Bias OUT
Installation Notes:
If Termination is required, a 120Ω resistor can be
placed across the D and E terminals by setting
SW1-5 to ON.
This converter has 1.2 KΩ pull-up/down bias
resistors built in. To use this bias, set SW1-6 and
SW1-7 to ON.
B&B Electronics’ RS-485 Application Note contains
more information about termination and biasing.
This reference is available on our web site.
RS-422
(Full Duplex)
1. Loosen the screws to open the TB lead clamps for the
A, B, C, D, and E terminals.
2. Insert the RS-422 signal leads. The terminal board
accepts 28 to 14 AWG wire.
3. Tighten the screws to close the TB lead clamps.
Ensure the clamps hold the leads securely. However,
do not over tighten. For Class 1 DIV 2 installations,
ensure the wiring is in accordance with the special
precautions and the specification table.
4. Configure the DIP Switch on the bottom of the
converter for RS-485 2-Wire operation (see above).
X. ON = Termination IN
OFF=Termination OUT
Y. ON=TX Bias IN
OFF=TX Bias OUT
Z. ON=RX Bias IN
OFF=RX Bias OUT
Installation Notes:
If Termination is required, a 120Ω resistor can be
placed across the D and E terminals by setting
SW1-5 to ON.
This converter has 1.2 KΩ pull-up/down bias
resistors built in. To use this bias, set SW1-6 and
SW1-7 to ON.
B&B Electronics’ RS-485 Application Note contains
more information about termination and biasing.
This reference is available on our web site.