If you are going to use the command line utility to receive data from the sensors then you should start it with QProcess and react when dataReady() Is signalled. Read the available data on to the end of a QByteArray buffer and then, for each full line in tHe buffer, parse the line, update your GUI, and remove the line from the buffer. In this approach the Qt program does not poll for data, it just waits to receive it.

If you are going to build the receiving code into your program then a different approach will be required.