USB to RS-232, RS-485 RJ45 VersaCom Serial Interface Adapter

Part: 687U-OEM   Model: SeaI/O-687U-OEM


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The SeaI/O 687U-OEM easily adds eight RS-232 or RS-485 serial ports to OEM computing platforms including ITX, EBX, EPIC, and ATX designs, or any OEM application where serial devices can be connected via an available USB port. With the unique VersaCom multi-interface connector design, both RS-232 and two-wire RS-485 signals are always present and active on the RJ45 serial connectors. Simply select the appropriate pin out for RS-232 or two-wire RS-485 on each individual port. There are no jumpers or switches to set, so field installation and service is easy.

The serial ports appear as standard COM ports to the host system enabling compatibility with legacy software. The SeaI/O 687U-OEM supports data rates to 921.6K bps and is designed with a state-machine architecture that greatly reduces the host CPU overhead when communicating over multiple ports simultaneously. Status LEDs on the RJ45 connectors display transmit and receive data activity.

The SeaI/O 687U-OEM is powered from your 9-30VDC source, or select from a variety of Sealevel power supply options. For conveniently powering serial peripherals, the supplied power is fused and connected to pin 5 on each of the RJ45 serial connectors. A high-retention USB type B connector helps to prevent accidental disconnection of the USB cable.

To further simplify connecting to Sealevel VersaCom RJ45 serial connectors, we offer a number of accessories including RJ45 modular adapters. With these helpful adapters you can easily connect to serial ports on virtually any PLC or peripheral regardless of the serial connector type or gender. For more information please browse our full line of adapters and converters.

An RS-485 pass-through connector on the side of the SeaI/O 687U-OEM provides additional I/O expansion using SeaI/O N-series OEM expansion boards. Increase your I/O network with up to 246 additional SeaI/O expansion boards, available with Reed and Form C relays, optically isolated inputs, TTL interfaces, A/D and D/A functionality.

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Additional information



Communications Chip



7.5 (L) x 5.0 (W) x 0.8 (H)

Electrical Interface

RS-232, RS-485

Extended Temperature

Call for Options

Humidity Range

10 – 90% Relative Humidity, Non-Condensing

Host Interface(s)


Max Data Distance

50 feet (RS-232)4000 feet (RS-485)

Max Data Rate

921.6K bps



Operating Temperature

0°C to 70°C (32°F to 158°F)

# of Ports


Power Requirement

9-30 VDC @ 2.5W

RoHS Compliant


Storage Temperature

-50°C to 105°C (-58°F to 221°F)

USB Specification

1.1 Compliant, 2.0 Compatible

  • Compliant with RoHS and WEEE directives
  • Utilizes high speed UARTs with 128-byte Tx FIFOs and 384-byte Rx FIFOs
  • Provides 8 RJ45 serial ports with Tx/Rx status LEDs
  • Integrates transmit and receive LED indicators on each port
  • VersaCom design allows RS-232 or two-wire RS-485 selection via cabling on each individual port
  • High-retention USB type B connector prevents accidental disconnection of USB cable
  • Input power via terminal block or barrel connector
  • Includes four 3/4 metal standoffs with nuts
  • Includes 72 USB A to B cable (Item# CA179)

Windows Software

Software: SeaMAX - Windows

Linux Software

Software: SeaMAX - Linux


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