422LP9TB

422LP9TB Datasheet

422LP9TB-3803-1/2

Part	Datasheet
422LP9TB	422LP9TB (pdf)

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B&B ELECTRONICS PRODUCT INFORMATION 422LP9TB-3803-1/2 Model 422LP9TB Two Channel RS-232 to RS-422 Converter CE The 422LP9TB is a port-powered two-channel RS-232 to RS-422 converter. It converts TD and RD RS-232 lines to balanced RS-422 signals. The unit can be powered from the RS-232 handshake lines, DTR and RTS. If port powering the unit, one of these handshake lines must be asserted high in order to power the unit See Table The RS-422 driver is enabled when RTS is asserted. Therefore, RTS must be asserted in order to transmit data. The RS-422 receiver is always enabled. If DTR is always asserted and the RTS is used to control the driver, the 422LP9TB can be used as an RS-232 to RS-485 4-wire converter. To insure reception, it is recommended that DTR is asserted or power the unit externally . In order to maximize the amount of power available to the RS-422 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. RTS State Low High Table 1 DTR State Functions Possible when port powering unit none High Receive Transmit, Receive High Transmit, Receive * NOTE Low = disasserted and High = asserted Connections The 422LP9TB can be connected in three different type of systems RS-422 Figure 1 , four-wire RS-485 Figure 1 , and two-wire RS-422 Figure Regardless of the system, the 422LP9TB 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-422 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. Integrate Expand Simplify International Headquarters: 707 Dayton Road P.O. Box 1040 Ottawa, IL 61350 USA 815-433-5100 Fax 433-5104 Westlink Commercial Park Oranmore Co. Galway Ireland +353 91 792444 Fax +353 91 792445 B&B ELECTRONICS PRODUCT INFORMATION 422LP9TB-3803-2/2 Biasing Resistors The biasing resistors for the RS-422/RS-485 receiver are 4.7K Ohm resistors. These resistors are labeled R1 and R6 See Figure Refer to B&B Electronics RS-422/485 Application Note for further information on biasing. Integrate Expand Simplify Figure 3 Specifications Data Rate 115.2K Baud max. Power: Port Powered from RTS and DTR. Note If external power is required, use a source that can supply 12 to 16VDC at 40mA 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. DECLARATION OF CONFORMITY Manufacturer’s Name: B&B Electronics Manufacturing Company Manufacturer’s Address:

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B&B ELECTRONICS PRODUCT INFORMATION
422LP9TB-3803-1/2

Model 422LP9TB

Two Channel RS-232 to RS-422 Converter CE

The 422LP9TB is a port-powered two-channel RS-232 to RS-422 converter. It converts TD and RD RS-232 lines to balanced RS-422 signals. The unit can be powered from the RS-232 handshake lines, DTR and RTS. If port powering the unit, one of these handshake lines must be asserted high in order to power the unit See Table The RS-422 driver is enabled when RTS is asserted. Therefore, RTS must be asserted in order to transmit data. The RS-422 receiver is always enabled. If DTR is always asserted and the RTS is used to control the driver, the 422LP9TB can be used as an RS-232 to RS-485 4-wire converter. To insure reception, it is recommended that DTR is asserted or power the unit externally .

In order to maximize the amount of power available to the RS-422 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.

RTS State

Low High

Table 1

DTR State

Functions Possible when port powering unit
none

High

Receive

Transmit, Receive

High

Transmit, Receive
* NOTE Low = disasserted and High = asserted

Connections

The 422LP9TB can be connected in three different type of systems RS-422 Figure 1 , four-wire RS-485 Figure 1 , and two-wire RS-422 Figure Regardless of the system, the 422LP9TB 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-422 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.

Integrate Expand Simplify

International Headquarters:
707 Dayton Road P.O. Box 1040 Ottawa, IL 61350 USA 815-433-5100 Fax 433-5104

Westlink Commercial Park Oranmore Co. Galway Ireland +353 91 792444 Fax +353 91 792445

B&B ELECTRONICS PRODUCT INFORMATION
422LP9TB-3803-2/2

Biasing Resistors

The biasing resistors for the RS-422/RS-485 receiver are 4.7K Ohm resistors. These resistors are labeled R1 and R6 See Figure Refer to B&B Electronics RS-422/485 Application Note for further information on biasing.

Integrate Expand Simplify

Figure 3

Specifications

Data Rate 115.2K Baud max.

Power:

Port Powered from RTS and DTR.

Note If external power is required, use a source that can supply 12 to 16VDC at 40mA

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.

DECLARATION OF CONFORMITY

Manufacturer’s Name:

B&B Electronics Manufacturing Company

Manufacturer’s Address:

Notice: we do not provide any warranties that information, datasheets, application notes, circuit diagrams, or software stored on this website are up-to-date or error free. The archived 422LP9TB Datasheet file may be downloaded here without warranties.

Datasheet ID: 422LP9TB 521485