Opto-Isolated USB to RS232 / RS485 / RS422 Converter (Industrial / Port-Powered)


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The USB-Serial-3 is a rugged, industrial-grade, optically-isolated USB to RS232 / RS485 / RS422 converter, which can be used to convert any standard USB port into a three-wire RS-232 port, a two-wire RS-485 port, or a four-wire RS-422 / RS-485 port and vice versa. This industrial opto-isolated USB to RS232 / RS485 / RS422 converter uses the latest chipset from Silicon Labs and is fully compatible with Windows 10 / 8 / 7 / Vista / XP / Server2003 / 2000 (32-bit), Windows 10 / 8 / 7 / Vista (64-bit), Win CE (5.0, 6.0), Mac OSX, and Linux (4.x.x, 3.x.x, 2.6.x). It supports multi-drop RS485 / RS422 networks and can be used to communicate with one loop of up to 128 units of RS485 or RS422 devices; when working with RS-485 signals, the CommFront’s auto-turnaround feature eliminates the need for flow control. This USB to RS232 / RS485 / RS422 converter operates within a temperature range of -40ºF to 185ºF (-40ºC to 85ºC), features 600W surge protection, 15kV static protection and 2500V opto-isolation circuitry, which effectively protect your USB devices from ground loops, noise problems, transient surges, remote lightning and spikes. The device comes with a built-in selectable 120-Ohm terminator for system reliability and easy installation. The unit is powered from the USB port and it features data format auto-sensing and self-adjusting; therefore, no DIP switch or jumper settings are required. And thanks to the professional and unique casing design, the product can be mounted directly on a wall, panel or DIN Rail, without a need of using any unsecured DIN-Rail or wall-mount brackets.

CommFront's products quality is ensured by our ISO-9001 quality control system (Cert No. SG12/04213, strictly certified by SGS), and we back our high-quality products with a 5-year replacement warranty and a 30-day risk-free money-back guarantee.

Note: the latest drivers (chipset: Silicon Labs CP210x) are available at: 


  • Rugged industrial-grade opto-isolated USB to RS232 / RS485 / RS422 converter.
  • Adds one RS-232, RS-485 or RS-422 port to your USB port.
  • USB port-powered, no external power required.
  • Industrial grade enclosed in a rugged, rustless ABS housing.
  • Supports multi-drop RS485 / RS422 networks (up to 128 nodes).
  • 2500V optical isolation.
  • 300 to 115.2K Baud operation (auto-sensing and self-adjusting).
  • Direct DIN-Rail (Rack) or Wall / Panel mounting (stackable).
  • Plug and play (hot-pluggable, data format auto-sensing and self-adjusting).
  • Data direction auto-turnaround, no flow control is required.
  • Built-in 120Ω end-of-line terminator for system reliability and easy installation.
  • Supports Windows 10 / 8 / 7 / Vista / XP / Server2003 / 2000 (32-bit), Windows 10 / 8 / 7 / Vista (64-bit), Win CE, Mac, and Linux.
  • Operating temperature: -40ºF to 185ºF (-40ºC to 85ºC).
  • Built-in 600W surge protection, 15kV static protection and circuit protection.
  • Surface Mount Technology manufactured to RoHS and ISO-9001 standards.
  • Safety: Strictly certified by TUV (Cert No. SG-CE-100004; SG-FCC-100001).
  • 5-year manufacturer's warranty.


Part Number: USB-Serial-3
Compatibility: USB 2.0 and EIA/TIA RS-232 / 485 / 422 standards
Power Source: From USB port
Current Consumption: Less than 200mA
Optical Isolation: 2500Vrms (AC, 1 min)
Baud Rates: 300 to 115,200bps (auto-sensing & self-adjusting)
Distance: USB: 10ft (3m); RS-232: 16ft (5m); RS-485 / 422: Depending on the power from USB port, will transmit up to 4000ft (1.2km) at 19,200bps
Connectors: USB: Type B male; RS-232 / 485 / 422: 10-Way Terminal Block
Accessories: 1x 5ft (1.6m) USB extension cord (Type B female to Type A female)
Maximum number of drops: RS-232: 1; RS-485 / 422: 128
End of Line Terminator: 120Ω (built-in, selectable)
Surge protection: 600W
Static protection (ESD): 15KV
Dimensions (H x W x D): 4.5 x 3.6 x 0.9 in (115 x 73 x 33 mm)
Weight: 4.2 oz (120 g) (with terminal block)
Operating Temperature: -40ºF to 185ºF (-40ºC to 85ºC)
Operating Humidity: Up to 90% RH (no condensation)





CommFront products are strictly certified by SGS and/or TUV - the Nationally Recognized Testing Laboratories [NRTLs] in North America (approved by OSHA) and the Notified Bodies in the European Union. Learn More




CommFront products are designed and manufactured to ISO 9001 standards. Our quality control system is strictly certified by SGS (Cert No. SG12/04213). Learn More




CommFront products have been proven to be reliable. We back our high-quality products with a 5-year replacement warranty and a 30-day risk-free money-back guarantee. Learn More

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