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IHV24AT: 3 KV Isolated RS232 to RS485 2 Wire Half Duplex Converter(Industrial Strength)


IHV24AT with Box

IHV24AT Box Label

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

Product Features:

  • This 3KV Isolated auto transmit unit features bi-directional serial conversion from RS232 to RS485 in 2 wire half-duplex communications mode.

  • Optimized for Isolated office/indoor/outdoor point to point, or multi-drop systems. It can drive 32 standard loads at 4000 ft. at data rates up to 115.2 Kbps.

  • The RS485 transceiver is protected by 27 Ohm/2 Watt series power resistors, auto-reset fuses, a transient suppressor bridge, and built-in ESD tolerance.

  • 3KV galvanic isolation helps eliminate noise and protect the equipment from destructive transients often found in industrial environments. Grounding options contribute to this protection.

  • Transparent to all asynchronous data, with any combination of data, parity, and stop bits, at data rates up to 115.2Kbps. No need to set jumpers or switches. 

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

  • Jumpers allow the RS485 termination,the bias resistors, and the RS232 DTE/DCE mode to be user configured. Jumper J5 will place the unit in Loop-Back mode for self test.

  • Edge mounted LEDs display regulated and isolated power, and RX and TX data activity at both interfaces. 

  • Pull-up resistors are built-in to accomodate RS232 devices that need inputs: CTS, RTS, and DSR. This unit does not require these, or any other control signals, to operate at maximum performance. 

  • A polarity protected switching power regulator accepts supply voltages from 9 to 35VDC, 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 connectors are an RJ11/12 telephone style for the RS232, a 3 pin removeable terminal strip for the RS485, and a 2 pin screw terminal strip and a 2.1 mm barrel connector for the power. 

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

  • Conformal coating, cables, and connectors, are factory options. 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. 

  • R E Smith Inc has similar converters with comparable/enhanced performance. They feature different connectors, LEDs, and termination options. Check out the IRSFC24, IRSFC24H, IRSFC24FB, and IRS422HV. 

  • We also have a new series of Converters and Repeaters that extend the RS485 communications distance far beyond conventional limits.

  • 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 IHV24ATrevA2.pdf Converter Schematic and Physical Rev A2


RS232: 3-wire interface to RJ11/12 Connector (TX, RX, Common)
RS485: 3-wire removeable screw terminal strip (RxTx+, RxTx-, Common)
Power: 2.1mm barrel connector and 2 pin screw terminal strip
LEDs Edge mounted regulated and isolated power, RS232, and RS485 Data activity
Bias: 470 Ohm pull-up and pull-down (jumper selectable)
Termination: 150 Ohm (jumper selectable)
Protection: Series resistors, transient suppressors inside a diode bridge, auto-reset communications fuses, Sipex SP485REP/EEP Transceiver with built-in ESD tolerance, 3KV optical isolation


Distance: Up to 4000 ft. (1220 meters)
Operation: 2-wire half-duplex RS485
Format: Asynchronous data with any combination of data, parity, and stop bits
Speed: Up to 115.2Kbps
Environmental: -40C to +85C ambient, 10-90% RH non-condensing
Supply Power: 9-35VDC at 0.5 Watts typical + external loads
Size: 3.50" X 3.00" X 0.9" (PC Board), with connectors: 3.50" X 3.25"
Mounting: 4-Holes at 3.00" X 2.25" (built-in standoffs for #6 hardware)

Options and Ordering Information:

IHV24AT: $119.00 ea. (Circuit board only)
Enclosure: $10.00 ea. (Medium)
Cable: $7.50 ea. (RS232, 7 ft., specify DB9F-7 or DB25F-7)
Supply: $8.50 ea. (12VDC/0.5A switching regulated wall power supply). Meets California, and most world wide safety and efficiency standards.

This is the IHV24AT unit showing the complete order number

IHV24AT with all options (DB9F cable/Enclosure/PS): Order Number: IHV24AT-B9FSPS @ $145.00 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: IHV24AT

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