It has been noted that some customers using v6.7.4 (current latest version of the SiLabs CP210x drivers) see connectivity issues with BIT or SCUI.exe
To work around this, please use the 6.7.0 version of the SiLabs drivers, which work without issue.
To access the 6.7.0 version of the SiLabs CP210x drivers, please go to this page: http://www.silabs.com/products/development-tools/software/usb-to-uart-bridge-vcp-drivers and select the second drive type listed (v6.7), as highlighted below: