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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.
SMFCOMX: Configurable Fiber Optic Repeater/Converter Platform


SMFCOMX with Box


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

Functional Description
  • This versatile product employs a modular approach to fiber optic repeater/converter design.

  • The three position (X,Y, and Z)Platform/Mother Board can be configured, at the factory or in the field, to provide functions that would otherwise require several different unit

  • There are two types of fiber interface modules available, which can be used in the "Y" and "Z" positions:

  1. Multi Mode(MMF) With ST connectors. One strand in each direction. Up to 1 km guaranteed(1 mile typical)at data rates up to 921.6 Kbps.

  2. Single Mode(SMF) With SC or LC Connectors. One strand carries data in both directions. Up to 12 miles at data rates up to 921.6 Kbps.

  • There are four types of copper interface modules available, which can be used in the "X" position:

  1. RS232 (isolated) Full Duplex to 460.8 Kbps

  2. RS485 (isolated) Half Duplex to 921.6 Kbps

  3. USB(non-isolated, mini USB) Full Duplex to 921.6 Kbps

  4. TTL(isolated, low true) Half duplex to 921.6 Kbps(In developement. Please call).

  • By populating the mother board with these modules, we fulfill the most popular fiber optic needs:

  1. Copper to fiber converter. Choose from four types of copper modules, and two types of fiber modules.

  2. Fiber to fiber repeater. Either Single Mode or Multi Mode fiber.

  3. Fiber to fiber converter. Single Mode to Multi Mode fiber.

  4. Fiber to fiber converter or repeater with Copper tap point.

  5. Copper to fiber distribution amplifier


  • Transparent to all asynchronous data, with any combination of data, parity, and stop bits, at data rates up to the maximum of the selected interface modules.

  • Fully automatic. No user jumper settings required When the RS485 interface module is used in slot "X", it features fast auto turn-around, from transmit to receive mode. It requires no software delays and eliminates timing problems and data collisions. We pioneered and perfected this leading edge technology.

  • The RS485 bias resistors(620 Ohms) and the termination resistor(220 Ohms) are jumper selectable. A transcient suppression bridge helps protect the circuits from external EMI commonly found in industrial environments.

  • Edge mounted LEDs display power and data activity at each of the three ports. The two fiber ports also have a "connect" LED(SMF mode only)

  • A polarity protected efficient switching power regulator accepts supply voltages from 9 to 35VDC, at 7.5 Watts max.

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

  • User connectors are removeable screw terminal strips for the copper communications and power(also a barrel connector for the power).

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

  • Accessories available are a 12VDC/1A Switching Power Supply(Wall Wart), an enclosure, and cables appropriate for the configuration.

  • Conformal coating, and other factory options are available. Contact us for options help.

  • 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. We also have a new series of Converters and Repeaters that extend the RS485 communications distance far beyond conventional limits. Contact us for information on these leading edge problem solvers. 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 SMFCOMXrevA.pdf Converter schematic/physical Rev A
pdf icon SMFCOMXrevA-CG.pdf General Configuration Guide
pdf icon SMFCOMXrevA-SS.pdf Physical Drawing
pdf icon TR-PR-SMFCOMX-SV Press Release


RS232: 3 pin screw terminal strip (TX, RX, Common)
RS485: 3 pin screw terminal strip (TX/RX-, TX/RX+, Common)
TTL: 3 pin screw terminal strip (TX, RX, Common)
USB: Mini USB-B Receptacle(Mates with Standard USB-A to mini USB-B cable)
Power: 2 pin screw terminal strip, and 2.1mm barrel connector (9-35VDC)
LEDs None
Bias and termination: RS485: 620 Ohm bias, 220 Ohm termination(jumper selectable)
Protection: Sipex SP485 EEP/REP Driver with built in ESD tolerance


Distance: Fiber: 12 miles(SMF), 1 km(MMF), Copper: 4000 ft(RS485), 50 ft(RS232 and TTL), 30ft(USB)
Operation: Fiber: MM and SM, Copper: Half duplex(RS485, and TTL), Full duplex(RS232, and USB)
Format: Asynchronous data with any combination of data, parity, and stop bits(Automatic. No user settings)
Speed: Fiber, RS485, USB, and TTL: 921.6 Kbps, RS232: 460.8Kbps
Environmental: -40C to +85C ambient, 10-90% RH non-condensing
Supply Power: 9-35VDC at 7.5 Watts max
Voltage: 8-15VDC
Size: 4.75" X 3.50" X 0.9" (PC Board), with removeable connectors: 5.00" X 3.75"
Mounting: 4-Holes at 4.00" X 3.00" (built-in standoffs for #6 hardware)

Options and Ordering Information:

SMFCOMX: Mother board with no plug-in modules: $135 each
Copper module for slot "X"(4 types): $75 each
Multimode Fiber module for slots "Y" and "Z": $85 each
Single Mode Fiber module for slots "Y" and "Z": $265 each
Enclosure: (Large): $12.00 each
Cables: Fiber test cables(Multi or Single Mode): 1 Meter: $32 each, 2 meter: $33 each, 6 ft USB-A to Mini USB-B: $4.75 each
Power Supply: $10 ea. (12VDC/1.0A switching regulated wall power supply) Meets California, and North American safety and efficiency standards(CE Certified at additional cost).

The complete order number is determined by the various modules installed. Please contact the factory, or Ron at 513-874-4796 or 513-638-0228(Cell).


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