The Firmata.js simply detect that no protocol version has been received, the protocol version request will be send. However, if the protocol version is detected and the firmware version is not detected, it will not send firmware version request, which will result in an unsuccessful connection.
The Firmata.js simply detect that no protocol version has been received, the protocol version request will be send. However, if the protocol version is detected and the firmware version is not detected, it will not send firmware version request, which will result in an unsuccessful connection.
Ref: https://github.com/firmata/ConfigurableFirmata/pull/144