M550/M560 Set Analogue Output Pass Code
Set the Analogue Pass Code in the node. This enables other functions to alter the node's analogue output calibration data.
Use this function with data set to zero to clear the Analogue Pass Code.
N.B. The pass code remains in its current state until one of the following -
1) The M560 is re-booted
2) The Analogue Pass Code is cleared
3) The General Pass Code is cleared
4) There has been no 4X register write functions for 6 minutes.

This function requires the General Pass Code to be valid.