Indicates whether the GPS has processed any new messages during the last read().
This function is provided to help cut out any unrequired processing in your own project code - ie if all of the GPS data is unchanged from the last time then it may well be that your code doesn't need to take any action.
Where Gps is the name you have given to the device in Project Designer.
A return value of TRUE just means that a message has been received - not that the values in the message have been changed from last time. For example: if your robot is standing still and a new message specifying the current longitude and latitude has been received then this will return TRUE - but the actual longitude and latitude values may still be the same since the robot isn't moving.
Hence this function can be used to indicate that we are receiving messages from the GPS.