USB to 8-Port RS-232, RS-422, RS-485 (Software Configurable) DB9 Serial Interface Adapter

Part: 2833   Model: SeaLINK+8M.SC

(1 customer review)

Call for price

Need some help? Contact us


The SeaLINK® 2833 USB to serial interface adapter provides eight serial ports that are software configurable for RS-232, RS-422, or RS-485, eliminating the need to open the enclosure to change jumper settings or dipswitches. The device maintains the electrical interface settings locally, allowing the host computer to be repaired or upgraded without reconfiguring the serial ports. Additionally, the 2833 can be configured at one computer and deployed to other computers.

Sealevel SeaCOM USB software drivers and utilities make installation and operation easy using Microsoft Windows operating systems. After installing the software, simply plug the 2833 into an available USB port and the serial ports are recognized as standard COM ports by the host system enabling compatibility with legacy software. All Sealevel SeaLINK USB serial adapters use a state-machine architecture that greatly reduces the host computer’s overhead when communicating over multiple serial ports simultaneously while supporting data rates to 921.6K bps. Status LEDs on the front of the enclosure indicate power, serial data activity, and electrical interface.

The 2833 is housed in a rugged metal enclosure and includes two convenient USB 1.1 hub ports for easily connecting additional SeaLINK devices and other standard USB peripherals. The adapter integrates Sealevel’s SeaLATCH locking USB ports, which are fully compatible with standard USB cables. When used with the included USB cable with a locking type B connector, the metal thumbscrew provides a secure connection to the device and prevents accidental cable disconnection. Also, the highly-retentive type B connector helps prevent unintentional separation from a standard USB cable. Both USB hub ports can be secured using optional SeaLATCH USB cables.

An industrial-grade wall-mount power supply with a locking DC connector that outputs 5VDC @ 6A is included. The input power is connected to pin 9 on each of the DB9 connectors for conveniently powering common 5V serial peripherals such as bar-code scanners, receipt printers, and signature input devices. Each serial port can provide up to 500mA to connected serial peripherals.

Standard operating temperature range is 0°C to +70°C and extended temperature range (-40°C to 85°C) is optional. The 2833 is fully compatible with the popular SeaI/O and Relio R1000 footprint, making it ideal for rugged and industrial environments.

Do you know that adapter design can impact your application? Find out how in this USB Serial Performance report.


Additional information



Operating Temperature

0°C to 70°C (32°F to 158°F)

Storage Temperature

-50°C to 105°C (-58°F to 221°F)

Software Configurable


Serial Connector(s)


SeaLATCH Locking USB


RoHS Compliant


Power Requirement

+5V @ 6A max.

# of Ports


Max Data Rate

921.6K bps

Communications Chip


Max Data Distance

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

Host Interface(s)


Humidity Range

10 – 90% Relative Humidity, Non-Condensing

High Retention USB


Electrical Interface

RS-232, RS-422, RS-485


7.5 (L) x 5.1 (W) x 1.8 (H)

USB Specification

1.1 Compliant2.0 Compatible

  • Compliant with RoHS and WEEE directives
  • Each port individually software configurable for RS-232, RS-422, or RS-485
  • Electrical interface settings are maintained across multiple computers
  • High speed UART with 128-byte Tx FIFO and 384-byte Rx FIFO
  • Supports data rates to 921.6K bps
  • Automatic RS-485 enable/disable
  • 5VDC input power passed through on pin 9 of each DB9M connector and fused at 500mA for powering serial peripherals
  • Sealevel’s SeaLATCH locking USB port provides secure connection with SeaLATCH USB cables via metal thumbscrews
  • SeaLATCH USB ports are fully compatible with standard USB cables
  • High-retention USB type B connector prevents accidental disconnection of standard USB cable
  • Includes two powered, fully-rated (500mA) USB 1.1 downstream hub ports
  • Status LEDs display electrical interface selection and serial data activity for each port
  • Power LED displays connection to host
  • Eight DB9M connectors with full modem control signals implemented in RS-232 mode
  • Sealevel SeaCOM software supports Windows 98SE/ME/2000/XP and Vista operating systems
  • Includes desktop AC power supply with a locking DC connector that outputs 5VDC @ 6A (Item# TR126) and US power cord (Item# CA248)
  • Includes 6′ USB type A to SeaLATCH USB type B device cable (Item# CA356)

Windows Software

Software: SeaCOM - Windows

Linux Software

Software: SeaCOM - Linux


Datasheet: 2833


Manual: 2833

1 review for SeaLINK+8M.SC

  1. DennisL

    Excellent product with equal customer service.
    I really can’t say enough good things about these serial to USB adapters or Sealevel as a company. Our project requires the timing of a range of precision custom sensors. They were for a long time reported to a DOS based computer with enough actual physical ports to grab all the needed data. As time has gone on all these systems are now EOL and need replacing but finding systems with dedicated serial ports at all is nearly impossible and finding them in the highest quality boards needed for data collection in harsh field conditions (hummidity, heat, cold, dust) is impossible.

    We started our testing by going with these junk serial converters from some Chinese knock-off firm. They were cheap (around 10 bucks per serial port) but were more trouble then they were worth. Even getting them running was a pain, I probably wasted a couple of thousand bucks in my own time just with the problems they caused, live and learn I guess. When we start to move out to actual field testing we bought a higher quality part from a know manufacture who I will not name. They were good up to a point, but if you exceeded 8 serial ports the drivers could no longer handle the load, they were also less then helpful at tech support. We ended up needing to make lots of virtual machine instances of windows and sending each USB port to one instance. This let us get up and running but required that you start the computer, start the VMs then plug each serial port into a specific USB port so you didn’t mess up the mapping. It was a total mess. After magooing my way though our busy season I decided we needed to find a better way.

    That is when we switched to the Sealevel systems. First off , I got even the most technical questions I threw at their engineers and sales people answered not only promptly but more importantly correctly and this was before I had purchased a single unit from them. After receiving the first unit the drivers for the older serial cards had messed up my windows install (I didn’t know this at the time) I called and was given a near super human effort by their support people to get it working without doing a total wipe and reinstall. After getting it working we have found nothing but good things with these boxes.

    Some examples:
    The drivers are great, I have found no upper limit yet on port per computer (I have 16 at the moment though I hear they max out somewhere around 256).

    There is an easy and straight forward way to find out every ports current physical location on the box. IE com13 = port8

    Indicator lights for what port is set to RS-232 and RS-422.

    They have excellent latency, we thought we had to live with a 30ms difference between our DOS system and the new USB system because of overhead. The Sealevel units quashed this down to a negligible 5ish ms.

    They come in a rugged metal shell and have been sitting baking in the Tx sun and humidity for the last 2 months (summer 2012) with no known problems. They have also been operating great in extreme vibration situations. The sealatch connectors are a god send.

    All in all these are great boxes, I won’t lie they are a bit on the expensive side but I can honestly say I probably lost 3x the price difference of these boxes in man hours trying to get cheaper options working.

Add a review

Your email address will not be published. Required fields are marked *