Frequently Asked Questions

Posted by Ariel Anders, Corey Walsh

Table of Contents

Common errors and fixes

Failed to connect to the VESC

Error message:

Failed to connect to the VESC, SerialException Failed to open the serial port to the VESC. IO Exception (16): Device or resource busy, file /tmp/binarydeb/ros-kinetic-serial-1.2.1/src/impl/unix.cc, line 151. failed..


  • Make sure Traxxas VESC battery is plugged in.
  • Make sure that USB hub on bottom of robot has a blue (power) light lit.
  • Make sure that the USB cable from the VESC is plugged into the VESC and the USB hub.
  • Try again, sometimes you retry a few times before it connects

Zed camera is plugged in but can’t find configuration

Generally this problem occurs when the camera is used for the first time and does not yet have the calibration parameters. If you have SSHed into the car with X-Forwarding, it can often download the parameters itself once it detects that they are missing. If you have not used X-Forwarding, you will get the following error…

Error message

No calibration file found for this ZED Camera. Trying to download it... 
QXcbConnection: Could not connect to display 
Didn't manage to load calibration file .. Setting file for your ZED may not exist on this PC.
 * Option 1 : Launch ZED Explorer App with --dc 12441
 * Option 2 : Manually download your calibration file by following the instructions on http://calib.stereolabs.com 
ZED SDK >> (Init) Failed to load Calibration Parameters...


  1. Make sure the car is connected to the internet
    • Ethernet cable should connect the wall port to the port on the router labeled “internet”
    • Verify that you have access to the internet: ping google.com
  2. Connect to the router with your computer and SSH into the car with X-Forwarding enabled
    ssh -x racecar@192.168.0.[Car #]
  3. Download calibration parameters fro mthe internet using the Zed Explorer tool
    /usr/local/zed/tools/ZED\ Explorer --download_calibration
  4. Test that it worked. This should take a few seconds to run…
    roslaunch zed_wrapper zed.launch