Writing data over Serial comm //Arduino & MPU6050 gyro+accelerometer
My preference is to use plain text for such data transfers - you can read the data with a terminal program to verify that the Arduino is sending what you think (or not!) to help isolate any problems.

I use a simple protocol (actually based on NMEA-0183) - form the data into "sentences", with a start-of-sentence character that won't occur in the data (I usually use "$"), then send the data items separated by commas, and ending with a newline or CR/LF.