What does the MADI phase boundary message mean?
Boundary Phase message explanation. MADI data is clocked asynchronously to the Sample Rate clock. The system uses the Sample Rate Clock ( Word Clock input to the MADI card ) input to mark the beginning of a new frame. E-MADI continually monitors the edges of the received MADI data signal and compares it with edges of the Sample Rate clock. Small adjustments are continuously needed to re-align to the Sample Rate Clock. When these re-adjustments are larger  the software reports them as a “Boundary Phase message” … with their adjustment value.

Messages in the range of +- 10 can be ignored.  Larger errors may indicate a slippage or delay between the MADI stream and the MADI card clock input.