Thanks for the email gtsuport, I have a contact there that I emailed earlier in the week, but he was busy (I found out yesterday after he replied to me).
I have figured out what I wanted, somewhat, and I'll give a little rundown.
We are using an Omron NX-102 controller and have multiple devices on EtherCAT. If a node was unplugged the line would still run until the part got to the unplugged tool. The line would just stop and look like it was running normal. If you connected a laptop to the PLC and ran the troubleshooter you would see the fault, but I wanted to annunciate that fault on the HMI. This is how you do it....
_EC_DissconSlavTbl - This is a system variable that shows the disconnected device (I haven't got this one to work yet)
_EC_PDSlvTbl - This system variable shows the processing data communicating slave table (This is the one that I can used to see if a device is working, drops low when it not)
So with my NX-102 we are allowed 192 nodes on EtherCAT. If node 20 drops out then _EC_PDSlvTbl[20] will be low. Now for the Cube67's, if a device that is connected to that node gets disconnected, that same bit will drop low, pointing you to the master. My next step is to figure out how to see which port on the Cube67 has issues.
Scott