Logo RS485 Authority
Questions? Custom builds? We build and support all of our boards.
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.


MHUBX8 with Box

MHUBX8 Box Label

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


Product Features

  • When used as a converter, the master RS232 port provides bi-directional serial conversion to the 8 RS485 distribution ports.

  • When used as a repeater, the master RS485 port provides bi-directional serial communications to the 8 RS485 distributation ports.

  • Data received into a distribution port is not transmitted out any other distribution port.

  • The RS485 drivers allow 32 standard loads at 4000 ft. at data rates up to 230.4 Kbps. When cascaded, this drive capability provides the means to form very large RS485 systems using "Star or Home Run" configurations.

  • Transparent to all asynchronous data, with any combination of data, parity, and stop bits.

  • Fast auto turn-around, from transmit to receive mode, requires no software delays, no jumper settings, and thus eliminates timing problems and data collisions.

  • The RS485 drivers feature enhanced ESD performance, and our design employs 22 Ohm series protection resistors.

  • Edge mounted LEDs display power and master port(s) data activity.

  • A polarity protected efficient switching regulator accepts supply voltages from 9 to 35VDC, at 0.5 Watts max.

  • Jumpers allow the RS485 distribution port termination resistors, and the receive function to be disabled.

  • The RS232 master port can be jumper configured as DTE or DCE.

  • Bias on the RS485 distribution ports is fixed to hold the port in idle mode if it is not being used, or is inactive.

  • The master RS485 port has jumper selectable bias and termination resistors.

  • User connections are compression screw terminal strips for the RS485 ports, an RJ11/12 telephone style connector for the RS232 port, and a 2.1mm barrel connector or 2 pin terminal strip for supply power.

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

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

  • Conformal coating, a 12VDC Switching Power Supply(Wall Wart), an enclosure, and a 7ft DB9F to RJ11/12 RS232 cable, are available. Please contact us for info about these option.

  • 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.

Product Description


Our unique auto transmit feature removes the burden of slowing down or spacing transmitted characters. After a character is transmitted, the RS485 transceiver is rapidly returned to the receive mode. No adjustments or tuning is required. This eliminates data collisions and lost characters due to slow turn-around. We pioneered this leading edge technology long before our competition.

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 technical 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 MHUBX8manual.pdf Manual
PDF MHUBX8RevE.pdf Schematic Rev E
PDF MHUBX8RevEss.pdf Physical drawing Rev E

Physical Properties and Features:

RS485: Compression Screw Terminal Strips
RS232: RJ11/12 Telephone Style Connector.
Power: 2.1mm baarrel connector, or 2 pin terminal strip.
LEDs Power, Data activity(TX: red, RX: green)


Distance: RS232: 10 to 100ft, RS485: 4000 ft at 230.4 Kbps
Operation: 2-wire half-duplex RS485
Format: RS232 or RS485 to 8 individual RS485 distribution ports
Speed: Up to 230.4 Kbps
Environmental: 0C to +70C ambient, 10-90% RH(non-condensing)
Supply Voltage: 9 to 35 VDC Provided by external power source
Power: Under 1/2 Watt(typical) + external load
Size: 5.6" X 4.0" X 1.4" (PC Board)
Mounting: 4 Holes at 2.25" X 3.0" (built-in standoffs for #6 hardware)

Options and Ordering Information:

MHUBX8: $209.00 ea. (Circuit board only)
Enclosure: $10.00 ea. (medium)
Data Cable: $7.50 ea. (RS232, 7 ft., Specify DB9F-7 or DB25F-7)
Power Adapter: $8.50 ea (wall wart type which meets most
California, and most world wide safety and efficiency standards)

This is the complete order number for the MHUBX8 with all available options:

MHUBX8 with all options (enclosure, cable, and power adapter): Order Number: MHUBX8-B9FSPS @ $235.00 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: MHUBX8

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