The HID® VertX® Network Controller RS-485 bus interface handles up to 16 V100, V200 and V300 VertX® modules.  There are two buses on every V1000 VertX® Network Controller which allows up to 32 modules (16 per bus) - 32 V100 door controllers could handle up to 64 doors and readers. 

This object's GUID can represent either bus (both show up in the component view as children of the V1000 Network Controller).  In the GUID above, Y=0 for bus 0 and Y=1 for bus 1.  The Ethernet MAC address is encoded into the last 12 digits of the GUID (represented by X's).  This object has only one property which is the number of modules connect to the bus.