Programming Help: how to read first value

I am using a NavX IMU board for our robot this year and I want the first value that the navx reads when the sub-vi is executed to become the set point in the PID function and the other values from the navx to be the process variable in the PID function. currently i have a button to set the set point value but i want the sub-vi to do this automatically. The Subvi takes the yaw value of the Navx and uses it to hold heading.

Any help is appreciated.

The easiest option would be to get the status of the board and wait for the connected Boolean to be true and calibration state is complete. You could use a feedback node to keep track when you trigger the storing of the set point so it won’t continue to update.