Bb-electronics 485LP9TBN - Datasheet User Manual download pdf

Document No. 485LP9TBN0712 - pg. 1/2

www.bb-elec.com order[email protected] suppor[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

Port Powered RS-232 to RS-485 Converter

Model 485LP9TBN

The 485LP9TBN is a port-powered two-channel RS-232 to RS-485 converter. It converts TD and RD RS-232 lines to

balanced RS-485 signals. The unit can be powered from the RS-232 handshake lines, DTR and RTS. One of these

handshakes must be high (asserted) to power the unit (See Table 1). DTR must be asserted to receive data. The RS-485

driver is enabled when RTS is asserted and disabled when RTS is disasserted. The RS-485 receiver is disabled when the

driver is enabled and is enabled when the driver is disabled.

In order to maximize the amount of power available to the RS-485 driver, the RS-232 handshake lines are not

looped back (tied together). As a result the following handshake lines will appear as disasserted (low): CTS, DCD, and

DSR. Care should be taken to insure that any software being used doesn’t require any of these handshake lines be

asserted. If existing software requires any of the handshake lines to be asserted, you can loop back the required

handshake lines in your cable.

Table 1

* NOTE: Low = disasserted and High = asserted

Connections

A typical two wire RS-485 connected is shown in Figure 1. Regardless of the system, the 485LP9TBN must be

connected with the proper polarity. With no data is 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 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.

RTS State

DTR State

Functions Possible

(when port powering unit)

Low

none

Low

High

Receive

High

Low

Transmit

High

Transmit

1 2

Summary of Contents

Page 1 - Model 485LP9TBN

Document No. 485LP9TBN0712 - pg. 1/2 www.bb-elec.com [email protected] [email protected] International Office: 707 Dayton Road PO Box 1040

Page 2 - DECLARATION OF CONFORMITY

Document No. 485LP9TBN0712 - pg. 2/2 www.bb-elec.com [email protected] [email protected] International Office: 707 Dayton Road PO Box 1040

Comments to this Manuals

No comments

Bb-electronics 485LP9TBN - Datasheet User Manual

Browse online or download User Manual for Accessories communication Bb-electronics 485LP9TBN - Datasheet. B&B Electronics 485LP9TBN - Datasheet User Manual

Summary of Contents

Comments to this Manuals

Related products and manuals for Accessories communication Bb-electronics 485LP9TBN - Datasheet