AR# 68521


UltraScale Boards and Kits - Failed to connect to Serial Port when using SCUI.exe


After successful installation of the Silicon Labs CP210x driver, and testing of the serial connection with a serial terminal (for example, TeraTerm), the SCUI tool cannot connect to the board.


This behavior can be due to the way in which the CP210x driver is identifying the virtual COM port.

On some PCs this will appear as follows:

"Silicon Labs Dual CP210x USB to UART Bridge: Enhanced COM Port"

On others it can appear as:

"Silicon Labs Dual Silicon Labs Dual CP2105 USB to UART Bridge: Enhanced COM Port" for example, or "Silicon Labs Dual Silicon Labs Dual CP2108 USB to UART Bridge: Enhanced COM Port". i.e. the "CP210x" is replaced by a fully numerated name.

The Windows Device Manager can be used to confirm how the driver is identifying.

Check the serial ports section, for example:

If the CP210x driver is showing up as CP2105 / CP2108 or anything other than CP210x, then it is necessary to change the SCUI configuration file (config.json).

To do this, follow the steps below:

1) Locate the config.json file that is packaged alongside the SCUI tool and open it in any text editor.

2) Search for CP210x and replace it with the numerical value you see in your Device Manager, for example CP2105 or CP2108. (There should be one instance near the bottom of the file)

3) Save the config.json file and close it.

4) Re-launch SCUI.exe. Now that the string matches the instance in Device Manager, the SCUI tool should connect to the board.

If you are still experiencing problems connecting to the SCUI, see (Xilinx Answer 69258).

Linked Answer Records

Associated Answer Records

Answer Number Answer Title Version Found Version Resolved
69258 UltraScale / UltraScale+ Boards - Incompatibility with latest version of SiLabs USB UART CP210x drivers N/A N/A
AR# 68521
Date 06/30/2017
Status Active
Type General Article
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