Port Powered RS-232/485 Converter

  • Extend RS-232 data signals up to 1.2 km (4,000 ft.)
  • Change RS-232 TD and RD to RS-485 signals
  • Automatic Send Data Control – no software drivers necessary
  • Baud rates up to 115.2 kbps
  • Powered from RS-232 handshake lines – no power supply required (optionally powered by an external 12 VDC power supply)


These port-powered, two channel converters allow your computer to communicate longer distances by converting TD and RD RS-232 lines to RS-485 signals. RS-485 also provides multi-drop capability.

All converters feature Automatic Send Data Control which enables the driver when data is present on the RS-232 side. Control of the driver is automatic at speeds up to 115.2 kbps.

Converters are powered by the RS-232 port DTR and RTS handshake lines. The unit is powered from the RS-232 data and handshake lines whether the lines are high or low. If the handshake lines are asserted (held High), and no termination is used, the port power efficiency is greatly increased.

Part Number RS-232 Connector RS-485 Connector Output Optional Power Supply
BB-485SD9R DB9 Female DB9 Female RS-485 2-wire
BB-485SD9TB DB9 Female Terminal Block RS-485 2-wire Yes
Serial Technology
Data Rate 115.2 kbps maximum
Connector 485SD9R: DB9 female
485SD9TB: DB9 female
Connector 485SD9R: DB9 female
485SD9TB: Terminal block
Biasing Resistors 4.7k Ohms
Source Port-powering: from RS-232 handshake lines
External power option, 12-16 VDC (485SD9TB only)
Power Connector Terminal block (485SD9TB only)
Input Voltage 12 VDC (485SD9TB only)
Power Consumption 40mA maximum
Dimensions 485SD9R: 6.0 x 3.2 x 1.6 cm (2.4 x 1.3 x 0.6 in)
485SD9TB: 8.7 x 3.2 x 1.6 cm (3.4 x 1.3 x 0.6 in)
Enclosure Plastic
Weight 0.18 lbs (81.6 g)
MTBF 485SD9R: 986473
485SD9TB: 968410
MTBF Calc. Method Parts Count Reliability Prediction
Operating Temperature 0 to +70 °C (+32 to +158 °F)
Storage Temperature -40 to +85 °C (-40 to +185 °F)
Operating Humidity 0 to 95% non condensing
Approvals / Certifications - 485SD9R, 485SD9TB
FCC Part 15, CISPR, EN 55022: 2010 + AC:2011 Class B Emissions
EN 61000-6-1: 2007 Generic Standards for Residential, Commercial and Light Industrial Environments
EN 61000-4-2: 2009 Electro-Static Discharge (ESD)
EN 61000-4-3: 2006 +A1 +A2 +IS1 Radiated Field Immunity (RFI)
EN 61000-4-4: 2012 Electrical Fast Transients-Burst Immunity (EFT)
EN 61000-4-6: 2009 Conducted Immunity

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