No Cortex Communication with Dell Tablets

Our district has purchased Dell Windows 8 Tablets for every middle and high school student.

The tablets have one USB port that happens to be a 3.0 port.

When we plug in to the Cortex and try to update firmware it starts and at 100% completion it throws an error and says there is no communication. It also tries to use a generic windows input device driver in place of the VEX Cortex driver.

I have been working on this problem for several weeks.

Any ideas???

Hello jrdesigns,

Thanks for taking the time to submit your problem.
In order to understand the issue a little bit better, can you please attach a screenshot of the error message? Also is the PC a 32-bit or 64-bit machine?

Please confirm.


32 bit, I will send more screenshots with machine information if needed

Dell Tablet Information

Dell Tablet Information1.JPG


Thanks for the screenshots.
Please perform a manual update of the firmware on the Microcontroller:
Click on Robot> Download Firmware> Manually Update Cortex> Master CPU Firmware> Standard File
After that, please click on Robot> Download Firmware> Manually Update Cortex> ROBOTC firmware> Standard File

Let me know your results.

ROBOTC.pdf (232 KB)

That is what I did for the in the first four screenshots that I sent. It starts and then stops and says no communication. We are not having any issues on any other machines, but these are the only machines we have tried with Windows 8 and USB 3.0 ports.


In that case, what I recommend is to manually re-install the 32-bit driver found here:
Let me know if this alleviates the problem.


Still no connection

Is there a VEX hotline or something to call???


We are still trying to figure out your problem, for now I recommend you to run the VEX Hardware using a Windows 7 64-bit machine (2.0 USB).

Our contact information can be found here:

I keep you updated.



It is normal for the Cortex download to be a virtual Comm port during part of the download and to temporarily transition to HID mode. Let us get your Cortex to a known state. Install the VEXnet Upgrade Utility located at This version, 4.1.7, fixes Win 8 issues.

To get your Cortex to a known state, on the VEXnet Upgrade Utility change “Default Code” to “ON”. Note the number to the right of “BootLoad”. If it is not “8”, please contact tech support for getting your Cortex or Joystick bootloader updated. If you do have bootloader 8, click “Bootload”, “Yes” and “Download” to put new Master and User Code in. The VEXnet Upgrade Utility does clobber the ROBOTC Firmware, so it will need to be reinstalled into the Cortex.

Now for ROBOTC. We duplicated your “ROBOTC Message “Failed to enter “Master CPU”…” message on our Dell Tablet. We opened ROBOTC as “Troublehoot compatibility” and saved the suggested settings. It fixed ROBOTC. We have successfully run ROBOTC as “Run as administrator” and we have run it normally. Our tablet has Win 8.1 Pro. If this does not help, please tell us the model number of your tablet so we can try to duplicate the failure.