Color QC and Matching Blog

Using a USB Adapter to Connect your Spectrophotometer to OnColor

Posted by Tom Merck on Fri, Apr 08, 2011

When you buy a new PC these days, it typically doesn't come configured with a serial port.  This once standard type of port has been replaced by USB ports.  However, many spectrophotometers still use serial communication and are supplied with a serial cable to connect to the PC. Then how are you supposed to connect your spectrophotometer to the PC if ti doesn't have a serial port? The solution is to use a Serial to USB adapter cable which allows you to connect your color computer via a USB port.

Connection to a color computer

The installation process can be tricky, so here are some things to remember when using a serial to USB adapter to connect your spectrophotometer to OnColor software:

  • Not all serial to USB adapters are created equal.  Cheap doesn't cut it when it comes to these devices.  Make sure you purchase one that is compatible with the operating system you plan to use it with.  So check that the drivers are included for whatever version of Windows you are running.
  • We've had great success with the Belkin model of USB to serial adapter.  While many other models may work fine, this brand gives consistent results.
  • Make sure you install the appropriate drivers.  A CD is usually provided with the cable.  Generally, you must install the driver BEFORE you plug in the cable to the USB port.
  • During installation of the driver, pay attention to what COMM port (communications port) the device is assigned to.  You will need to know this in OnColor when you go to establish communications with the spectrophotometer.  If you forgot to look, then go to:

 Control Panel



-->Device Manager


then look at the assignments for the comm port.  One of them should be assigned to your adapter.  Note the number of the comm port, as this is what you will need later in OnColor.

  • After installing the driver for the adapter and figuring what comm port it was assigned to, then you are ready to connect the spectro and establish communications with OnColor. Connect the adapter to the PC and to the spectro and be sure to turn on the power to the instrument.  In the Communications Dialog box, select the comm port that you noted in the previous step.  Then Test Settings and your communications should be successful.
  • If you get a message that says  " Error ( -2 ) COM port is not supported or is being used by another device," then the device is not setup properly or you have not installed the driver correctly.Spectrophotometer error message







Are you using a serial to USB adapter to connect your spectrophotometer to OnColor?  Is so, please comment below and tell us the brand you are using so that other users can benefit from your experience.

Tags: OnColor, USB adapter, color computer, color spectrophotometer