Error 4 indicates that file position pointer has reached the end of file (EOF) and it is not being reset to read the beginning of the file again. To fix this, create a shift register
and wire the boolean EOF?
value from the Read From Measurement File Express VI to the Reset
field of the same Express VI. A visual example of this can be seen below. This will force the Read From Measurement File Express VI to read from the beginning of the file again and should prevent the Error 4 message.