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Black metal USB-to-serial adapter with DB9 port and external DIP switch

CoolGear

CoolGear USBG-COMi-SI-M USB converter optical isolated RS-232/422/485

SKU CH-MMM1-0MM3X

Adds an optically isolated RS-232, RS-422 or RS-485 serial port via USB with 2000 V DC isolation and 25 KV ESD protection

  • Adapter typeUSB to DB9 (RS-232)
  • Product colorBlack
  • Adds an RS-232, RS-422 or RS-485 serial port via USB
  • 2000V DC optical isolation plus 25KV ESD surge protection
  • External DIP switch sets RS-232, RS-422 or RS-485 mode without opening the case
  • Automatic transmit and receive control for 2-wire RS-485 half-duplex
  • Installs as a standard Windows COM port on Windows 98 through 11, Linux and Mac OS 10.X

Industrial Serial Adapter

The CoolGear USBG-COMi-SI-M adds a single RS-232, RS-422 or RS-485 port to any system with a free USB socket. It targets engineers and integrators who must connect legacy POS terminals, factory automation gear, barcode scanners or long-distance data links without opening a chassis. The DB9 interface and external DIP switch let you select the required protocol on the bench or in the field.

Isolation and Signal Integrity

Optical isolation rated at 2000 V DC and 25 KV ESD surge protection shield the host computer from ground loops and transient spikes common in harsh environments. Automatic transmit and receive control manages the two-wire RS-485 half-duplex mode without software intervention. The adapter draws power from the USB bus and installs as a standard Windows COM port across Windows 98 through 11, Linux and Mac OS 10.x.

Mounting and Mode Selection

A SECC sheet-metal chassis includes built-in surface-mounting flanges and accepts an optional DIN-rail clip for cabinet installation. The external DIP switch changes between RS-232, RS-422 and RS-485 modes instantly, removing the need to dismantle the enclosure. Buyers who need multiple simultaneous serial ports or USB-C native connectivity will require a different solution.

How it compares

Measured against everything we stock in USB Adapter Cables & Dongles, at today’s prices. Recalculated every night.

Price $107.99
Pricier than about 91% of the 1,430 comparable items (median $14.99).

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Specifications

Product
Brand nameCoolgear
Model nameUSBG-COMi-SI-M
Product colorBlack
Adapter typeUSB to DB9 (RS-232)

Questions about this item

How do I select RS-485 mode on the USBG-COMi-SI-M without opening the chassis?

Use the external DIP switch on the case to choose RS-485; no cover removal is required.

What protection does the 2000 V optical isolation provide over time?

It continuously blocks ground-loop currents and 25 kV ESD events from reaching the host USB port.

Which signal lines are active in 2-wire RS-485 half-duplex mode?

Only Data- and Data+ are used; automatic transmit/receive control handles direction switching.

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