B&B Electronics 485DRJ - Datasheet - Manual

485DRJ-0812-1/2
www.bb-elec.com [email protected] [email protected]
International Office: 707 Dayton Road PO Box 1040 Ottawa, IL 61350 USA 815-433-5100 Fax 433-5104
European Office: Westlink Commercial Park Oranmore Co. Galway Ireland +353 91 792444 Fax +353 91 792445
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Model 485DRJ
Multidrop Your RS-485 Network Without
Splicing Your Cables
Includes Send Data Control and Two RJ Connectors CE
The 485DRJ is a port-powered, full-duplex or half-duplex RS-232 to RS-485 converter with send data control. The send
data control enables the driver without software intervention. The unit converts TD and RD RS-232 lines to balanced
RS-485 signals and supports two or four wire RS-485 communications. The converter is powered from the RS-232
handshake lines, RTS, CTS and DTR, DSR, CD. Only one of the handshake lines must be present and in any state to
power the converter. No handshake change is necessary so no software is required to control the lines. The RS-485
driver is enabled with each bit of data when in send data control mode. The RS-485 receiver is disabled when the driver
is enabled and is enabled when the driver is disabled. This prevents data from being echoed back into the RS-232
device. The RS-232 side has a DB-9 female connector. The RS-485 side has two six-position RJ11 connectors for easy
multi-drop connections.
Switches
Switches one and two are used to set up two or four wire mode. In the ON position the converter is in two-wire mode. In
the OFF position the 485DRJ is in four-wire mode. Switch three enables the transmitter. In the ON position, the
transmitter is enabled when data is sent. In the OFF position the transmitter is always enabled. Switch four controls the
receiver. In the ON position the receiver is enabled when data is not being sent. In the OFF position the receiver is
always enabled. To set the converter up as RS-422, turn OFF all switches.
Connections
Regardless of the system, the 485DRJ must be connected with the proper polarity. With no data being sent and the
driver enabled, the RS-232 line should be negative and the TD(A) should be negative with respect to TD(B).
Proper operation of any RS-485 system requires the presence of a signal return path between the signal grounds of the
equipment at each end of an interconnection. This circuit reference may be established by a third conductor connecting
the common leads of devices, or it may be provided by connections in each piece of equipment to an earth reference.
When the circuit reference is provided by a third conductor, the connection between the signal grounds and the third
conductor should contain some resistance (e.g. 100 ohms) to limit circulating currents when other ground connections
are provided for safety.
Specifications
Communication: Two or four-wire
Data Rate: 115.2K Baud max.
Power: Port-powered from handshake lines
Dimensions: 7.6 x 5.6 x 2.2 cm (3.0” x 2.2” x 0.9”)
Temperature Range: 0 C to 70C
Signal RJ11 Pin #
TDA(-) 2
TDB(+) 1
RDA (-) 5
RDB (+) 6
Signal Ground 4,3
Switch ON OFF
SW:1 Two-wire Four-wire
SW:2 Two-wire Four-wire
SW:3 SD control TD enable
SW:4 SD control RD enable