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Using the USB485 converter with Windows 10

The eGauge USB485 converter may be used as a standard serial-to-USB converter on a computer to read data from an eGauge or communicate with other third party devices besides the eGauge. The eGauge USB485 uses the FT230X chipset from FTDI. Up to date systems should already have the FTDI drivers available for use. If the FTDI drivers are not installed, drivers and information are available from the FTDI website at COM port downloads can be found at

This article describes how to verify the USB485 converter is recognized by a Windows 10 machine, and uses QModBus to show data being read from an eGauge via two USB485 converters.

Note that support for third party devices is not guaranteed. 


1) Connect the eGauge USB485 via USB to the Windows 10 machine. After a minute or several, a notification indicating the serial converter drivers are ready will be displayed at the bottom right-hand corner. If this does not appear after 5 minutes, verify the USB cable is secure and move to the next step.


2) Open the device manager by pressing the Windows Key and R (Win+R) to open the "Run" prompt. Alternatively open the start menu, and type "run" and press enter to open the run prompt. Enter devmgmt.msc in the text box and press "OK":

3) Under "Universal Serial Bus controllers" you should see "USB Serial Converter":

4) You can determine the COM port by expanding "Ports (COM & LPT)". Here, it is COM3:

5) The QModBus program may be installed from eGauge Systems does not endorse and cannot validate the legitimacy of the QModBus program. When the QModBus program is installed and executed, if no serial converters are found it will warn you:

6) If a serial converter is detected, the QModBus will default to use one that is found (in our case, COM3). Here, we have configured the serial settings to match with an eGauge Modbus slave connected via serial to this Windows computers USB485 converter. In the screenshot below, we read registers 1012 and 1013, as DC voltage is a 32-bit float starting at address 1012. When converting 0x4143 and 0xB07B as a big endian float, we see the DC voltage is about 12.23.