Matrix: How do I monitor HCI messages to / from the matrix or VSM

HCI monitoring : 

go to matrix event log > request info select custom
Enter 111 as the message code 
For parameter 1, enter 1 (enable); 0 (disable)
The following will turn on HCI debugging in the rack. It will be quite verbose so will flood the event log but at least you will be able to see if the message is being sent from VSM