B&B Electronics 485LPCOR Datasheet
485LPCOR-0812 -1/2
www.bb-elec.com orders@bb-elec.com support@bb-elec.com
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
PRODUCT INFORMATION B&B ELECTRONICS
DECLARATION OF CONFORMITY
Manufacturer’s Name: B&B Electronics Manufacturing Company
Manufacturer’s Address: P.O. Box 1040
707 Dayton Road
Ottawa, IL 61350 USA
Model Number: 485LPCOR
Description: Port-Powered RS-485 Converter
Type: Light industrial ITE equipment
Application of Council Directive: 89/336/EEC
Standards: EN 55022
EN 61000-6-1
EN 61000 (-4-2, -4-3, -4-4, -4-5, -4-6, -4-8, -4-11)
© 2003 by B&B Electronics. All rights reserved.
Model 485LPCOR
Port-Powered RS-485 Converter
The 485LPCOR is a port-powered two-channel RS-232 to RS-485 converter. It converts the TD and RD RS-232 lines to
balanced half-duplex RS-485 signals. The unit is powered from the RS-232 data and handshake lines whether the lines
are high or low. An external power supply can be connected to two pins on the RS-485 connector if no handshake lines
are available. The 485LPCOR has a DB-25 female connector on the RS-232 side and a DB-25 male connector on the
RS-485 side.
Robert M. Paratore, Director of Engineering RS-232 Side:
Connector: DB-25 Female
Signals: Passes through pins 2 (TD) and 3 (RD).
Pins 4 (RTS) and 5 (CTS) are tied together.
Pins 20 (DTR), 6 (DSR), and 8 (CD)
are tied together.
RS-485 Side:
Connector: DB-25 Male
Signals: Half-duplex two-wire operation only.
Automatic control circuit enables driver only
when transmitting.
Receiver is disabled when transmitting to prevent echo back
to RS-232 device.
Can transmit up to 4000 feet at 115.2k baud.
Power Requirements
No external power required if two RS-232 output handshake lines are available.
External 12VDC can be applied to pins on the RS-485 side between pins 25 (+) and 12 (GND) if handshake lines are
not available.
35mA current draw maximum under normal operation when externally powered.
NOTE: When using an external supply, the supply should be connected only to specifically labeled power
inputs (power jack, terminal block, etc.). Connecting an external power supply to the handshake lines may
damage the unit. Contact technical support for more information on connecting an external power supply to
the handshake lines.
Dimensions: 2.20 x 2.16 x 0.64 in ( 5.59 x 5.49 x 1.63 cm)
Connections and Operation
To DB-25 RS-232 DTE device: To DB-25 RS-232 DCE device: To RS-485 device or network:
Can use 25-pin straight through cable. Can use 25-pin cable that crosses pins 2 & 3.
485LPCOR-0812 -2/2
www.bb-elec.com orders@bb-elec.com support@bb-elec.com
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
PRODUCT INFORMATION B&B ELECTRONICS
© 2003 by B&B Electronics. All rights reserved.
Pin one is also connected straight through on the 485LPCOR from the RS-232 side to the RS-485 side so that the
shield can be passed through to earth ground if desired. It is recommended that shielded cable be used and that the
shield be connected to earth ground at one point in the system. See B&B Electronics’ RS-422/RS-485 Application Note
for further information on shielding.
Although the 485LPCOR uses the handshake lines to power
the converter, no handshaking is required to control the RS485 driver. The RS-485 driver is automatically enabled during
each spacing state on the RS-232 side. During the marking
or idle state, the RS-485 driver is disabled and the data lines
are held in the marking state by the 4.7K ohm pull-up and
pull-down resistors. The value of these resistors may need to
be changed to a different value when termination is used in
order to maintain the proper DC bias during the idle state.
See B&B Electronics’ RS-422/RS-485 Application Note for
more information on termination and DC biasing of an RS485 network.
The 485LPCOR has an internal connection to prevent data
transmitted from the RS-232 port from being echoed back to
the RS-232 port. The connection can be cut to have the
receiver always enabled. (See Figure 1.) After the connection
is cut, a jumper wire from pin 18 to pin 21 can be installed to disable the receiver during transmission.
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