Create device client handle

In order to communicate with Azure IoT devices, we get the device connection string after creating the device, and we need to use this string to create a device client handle.

Request:

"|4|2|1|connectionString|"

Parameters:

connectionString the device connection string

Returns:

"|4|2|1|1|\r" Create successfully

"|4|2|1|2|reason|\r" Fail to create

Parameters:

reason the reason why it failed

Arduino Sample:

softSerial.print("|4|2|1|HostName=DFIoT.azure-devices.cn;DeviceId=esp8266;SharedAccessKey=lSRhR5pG4YlCAYy3toCMkY0a6FINFv+tJ21o1lwcHos=| ");