Advantech BB-4WSD9TB RS232 422 485 Serial Converter

Advantech BB-4WSD9TB is a port-powered RS-232 to RS-422/RS-485 universal converter that translates a DB9 female RS-232 interface into RS-422 or RS-485 signals on a terminal-block output. It can be powered from the host via port-power or from an external 12 V DC supply through a power jack, offering flexible installation in equipment racks or enclosures. The device employs Automatic Send Data Control to manage RS-485 transmission automatically, enabling the transmitter from the RS-232 TD signal and, in 2-wire RS-485 half-duplex mode, enabling the receiver when not transmitting; in 4-wire RS-422/RS-485 full-duplex mode, the receiver remains enabled. A set of DIP switches selects the operating mode—RS-485 2-wire half-duplex, RS-485 4-wire full-duplex, or RS-422—with additional switches for Echo On/Echo Off to control the receive path behavior in 4-wire configurations. The BB-4WSD9TB is part of Advantech’s ULI-224 family of inline converters and ships in a compact enclosure measuring about 9.0 cm by 4.3 cm by 2.3 cm, designed for easy panel or chassis mounting. On the RS-232 side you’ll find a DB9 female connector, while the RS-422/RS-485 side uses a terminal-block connection suitable for 2-wire or 4-wire wiring, depending on the mode selected. The model name BB-4WSD9TB specifies a DB9F RS-232 to RS-422/RS-485 TB converter configuration, and the unit supports operation with either port power or an external supply, making it a versatile bridge between legacy serial devices and multi-drop serial networks.