B&B Electronics 4WSD9TB Datasheet

4WSD9TB-0712 - p1/5

www.bb-elec.com [e-mail] [e-mail]

International Office: 707 Dayton Road PO Box 1040 Ottawa, IL 61350 USA 815-433-5100 Fax [phone]

European Office: Westlink Commercial Park Oranmore Co. Galway Ireland [phone] Fax [phone]

PRODUCT INFORMATION B&B ELECTRONICS

Model: 4WSD9TB

Universal Converter

Covers All the Bases:

RS-232 to 4-wire RS-422, 2-wire or 4-wire RS-485

Highlights

Selectable RS-485 2-wire half-duplex, or RS-485 4-wire full-duplex operation
Selectable RS-422 operation - Transmit & Receive always enabled
DB9 Female RS-232 Connection, Terminal Blocks for RS-422/RS-485
Port power or External 12V DC power (jack)
Automatic RS-485 Driver Control - works without special programming

o Enables Transmitter from RS-232 TD signal
o Enables Receiver when not Transmitting (half duplex)

Built-in bridging switches for 2-wire or 4-wire modes – no external jumpers
Operating Mode Switches: 4

o Transmit mode, Receive Mode, and 2 switches for 4-Wire or 2-Wire
o Receiver mode: Echo On (4-wire) or Echo Off (2-wire RS-485)
o Two 4-wire/2-wire switches for full or half duplex (bridge) connections

Description

The 4WSD9TB Universal Converter provides RS-232 to RS-422/RS-485 conversion using either port-power or an
external power supply. Data is converted in both directions, RS-232 Transmit data is converted to balanced RS­422 or RS-485 Transmit, and Received RS-422/RS-485 signals are converted to RS-232. Unlike converters
which require programming hardware handshaking signals to control RS-485 or RS-422 operation, the 4WSD9TB
provides automatic control. In RS-485 mode, the RS-485 driver is enabled by circuitry which senses the RS-232
TD input. In half duplex RS-485 mode, the receiver is enabled when not transmitting. For full duplex operation,
the receiver is set always enabled. In RS-422 mode, the transmitter and receiver are always enabled. The
operating mode is set with 4 switches (Table 1). The 4WSD9TB is powered by the RS-232 signal lines whether
they are set high or low. If not enough power is available from the port, or no handshaking lines are available, a
DC jack is provided to connect a 12VDC supply. The DB9 female connector for RS-232 is wired as DCE (like a
modem).

Power

No external power is required if two RS-232 output handshake lines (RTS & DTR) are available and the
cable run is short. If the handshake lines are raised (enabled) and no termination is used, the power
efficiency is greatly increased. Less than 3mA is required to operate the 4WSD9TB plus the load current.
For applications that do not have handshake lines or require a large load current, power may be externally
supplied with a +12VDC power supply with a 2.5mm plug (tip positive).

RS-232 Operation

RS-232 connections require pins 2 (RD), 3 (TD), and 5 (Signal Ground). Pins 7 (RTS) and 8 (CTS) are
tied together, and pins 6 (DSR), 1 (DCD), and 4 (DTR) are also tied together. Any incoming data lines
in either the high or low state are used to port power the 4WSD9TB. The more handshake lines
available, the more likely the unit can be port powered. Table 2 shows the RS-232 pinout.

Refer to matching Figures 1 to 4 for each mode for typical connections. See Table 1, and set Switches 1-4
to match the Operating Mode. See Troubleshooting section for Loopback Test Mode.

4WSD9TB-0712 - p2/5

www.bb-elec.com [e-mail] [e-mail]

International Office: 707 Dayton Road PO Box 1040 Ottawa, IL 61350 USA 815-433-5100 Fax [phone]

European Office: Westlink Commercial Park Oranmore Co. Galway Ireland [phone] Fax [phone]

PRODUCT INFORMATION B&B ELECTRONICS

Switches

Switch 1 (Tx)

Switch 2 (Rx)

Switch 3 (bridge)

Switch 4 (bridge)

Operating Mode

RS-485 2-Wire Mode

(half duplex)

RS-485

Echo Off

2-Wire

2-Wire

RS-485 4-Wire Mode (full

duplex)

RS-485

Echo On

4-Wire

4-Wire

RS-422 4-Wire Mode

(full duplex)

RS-422

Echo On

4-Wire

4-Wire

Loopback Test Mode*

As Desired

Echo On

2-Wire

2-Wire

Table 1 – Switch Settings for Operating Mode

* Used with HyperTerminal or another terminal program to confirm operation of data through converter.