How to speed up serial communication on Windows

Posted on By Charity Carter

Changing the latency timer on a Windows PC can reduce the delay between transmitting two commands. Here is a step-by-step guide on how to do this!

  1. Open the Device Manager > Port (COM & LPT) > USB Serial Port (COM7). Note that the COM port number will likely be different on your machine.
  2. Right-click USB Serial Port and select Properties then navigate through
    Properties > Port Settings > Advanced.
  3. Using the Advanced tab, we can adjust the Latency Timer.
  • Step 1: Device Manager
  • Step 2: USB Port Properties
  • Step 3: Latency Timer

The latency timer controls the time interval between two commands in serial communication. We can confirm this by observing the communications signal on an oscilloscope.

  • Latency Timer set to 16ms
  • Latency Timer set to 8ms
  • Latency Timer set to 1ms

In the above, blue lines are commands sent from the PC and red lines are the Qontrol hardware response. We used two Q8b modules in this experiment, hence there are two commands and two responses.

And that’s it! We hope this short tutorial has helped you make the most of your Qontrol modules. If you have any questions, as always, please contact us and we would be happy to help!