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If you have a special application, we may already have a solution for you.
Give Ron a Call at 513-874-4796 or 513-638-0228 for additional information.
RSFC24W & RSFC24R:  RS232 to RS485 2 Wire Half Duplex Non-isolated Converters


RSFC24W Boxed

RSFC24W Box Label


RSFC24R Boxed

RSFC24R Box Label

"Let me spin a very large
RS485 network for you!"

  • This auto transmit unit features Bi-directional serial conversion from RS232 to RS485 in 2 wire half-duplex communications mode.

  • Optimized for non-isolated office/indoor point to point or multi-drop systems.

  • Transparent to all asynchronous data, with any combination of data, parity, and stop bits, at data rates up to 115.2Kbps. 

  • Fast auto turn-around, from transmit to receive mode, requires no software delays and eliminates timing problems and data collisions. A special jumper(J9) can further shorten the turn-around time to accommodate fast responding target devices. We pioneered this leading edge technology long before our competition.

  • The RS485 driver, with built in electro-static protection, allows 32 standard loads at 4000 ft. and data rates up to 115.2 Kbps.

  • Jumpers allow the RS485 termination and bias resistors, and the RS232 DTE/DCE mode to be user configured. Jumper J10 will place the unit in Loop-Back mode for self test. 

  • A polarity protected linear power regulator accepts supply voltages from 8 to 15 VDC, at 0.5 Watts max. 

  • Broad environmental range. Temperature: -40C to +85C(-40F to +185F). Humidity: 10 to 90% RH(non-condensing)

  • Four(4) easy mount through hole standoffs, which accept #6 hardware, are provided on the circuit board.

  • User connections are an RJ11/12 telephone style for the RS232, an RJ11/12 telephone style (R suffix), or a Wago style (W suffix) connector for the RS485 port, and a 2.1 mm barrel connector(power). Refer to the "Options and Ordering Information" below.

  • Accessories available are a 12VDC Switching Power Supply(Wall Wart), an enclosure, and a 7ft DB9F to RJ11/12 RS232 cable.

  • Conformal Coating, cable, and connectors, are factory options. Contact us for options help.

  • R E Smith also provides several functionally identical units with different connectors and LEDs: ASC24R, ASC24W, ASC24T, and ASC24TS.

  • R E Smith Inc makes a wide variety of isolated converters that address the electrical noise problems that contribute to unreliable communications, and product failure.  If what you see here is not exactly what you need, don't hesitate in calling us at 513-874-4796.

  • WARNING: Do NOT connect this device to a telephone system under any circumstances. Damage could result to the circuit board and/or your telephone system.

About R E Smith, Inc:

R E Smith, Inc. engineers and manufactures a comprehensive line of isolated and non-isolated converters, repeaters, multiport repeater hubs, fiber optic based products, and I/O boards. All our products are designed, built, tested, and shipped from our facility in the Greater Cincinnati Ohio area. We ship small quantities of most products from stock the same day, and larger quantities in a few business days.

We listen to you. We are customer driven. Many of our products were developed and improved due to suggestions and feedback from our word-wide customer base. They are being used at the South Pole, at the bottom of the sea, at the edge of space, and everywhere in between. Typical uses are very large networks, monitor and control of elevators, machinery, lighting, security, fire and alarm, access, cameras, military ground support, and much more. We provide free support, no-argument warranty repairs, and recommendations for your application. Challenge us with your communications problem. We may already have the solution. If your system keeps failing, or is unreliable, we have isolated, doubly isolated, noise resistant, cost effective, and proven solutions for difficult environments.

Related Files:

pdf icon RSFC24W/RrevB.pdf Converter schematic/physical Rev. B

Physical Properties and Features:

RS232: 3-wire interface to RJ11/12 Connector (TX, RX, Common)
RS485: 3-position Wago terminal strip(W suffix) or RJ11/12 connector(R Suffix)
Power: 2.1mm center positive "Barrel" connector (8-15VDC)
LEDs None
Bias: 620 Ohm pull-up and pull-down (jumper selectable)
Termination: 120 Ohm (jumper selectable)
Protection: Sipex SP485 EEP/REP Driver with built in ESD tolerance


Distance: Up to 4000 ft. (1220 meters)
Operation: 2-wire half-duplex RS485
Format: Asynchronous data with any combination of bits, parity and stop (auto mode)
Speed: Up to 115.2Kbps
Temperature:   -40C to +85C ambient
Humidity: 10-90% non-condensing
Voltage: 8-15VDC
Power: Under 1/2 Watt(typical) + external load
Size: 2.50" X 2.00" X 0.9" (PC Board), with connectors: 2.50" X 2.15"
Mounting: 4-Holes at 2.00" X 1.50" (built-in standoffs for #6 hardware)

Options and Ordering Information:

RSFC24W: $43.00 ea. (Circuit board only, with Wago terminals)
RSFC24R: $43.00 ea. (Circuit board only, with RJ11/12 connector)
Enclosure: $8.00 ea. (Small)
Cable: $7.50 ea. (RS232, 7 ft., Specify DB9F-7 or DB25F-7)   
Supply: $8.50 ea. (12VDC @ 200/300 mA wall power supply)

These are the two most common configurations showing the complete order numbers

RSFC24W with all options (DB9F cable/Enclosure/PS): Order Number: RSFC24W-B9FSPS @ $67.00 ea. (Qty. 1-9)

RSFC24R with all options (DB9F cable/Enclosure/PS): Order Number:RSFC24R-B9FSPS @ $67.00 ea. (Qty. 1-9)

Need a different configuration or more information? Give Ron a Call at 513-874-4796 or 513-638-0228(Cell)

Webstore: RSFC24W & RSFC24R

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