A b3 controller that is shown as offline in CyberStation can incorrectly change to online when RoamIO2 is connected to the bus.
RoamIO2 bCX CyberStation b3
When a RoamIO2 is connected to the MSTP bus and the BACnet Service Tool software is started, it assigns itself a BACnet MAC Address. It may assign itself the BACnet MAC Address of an offline b3. If at the same time you are running a listview of b3 controllers on that bus in CyberStation, and displaying commstatus, the offline b3 with that BACnet MAC address will appear online. However, attributes such as VersionNum, BACnet DeviceID, Port and InstanceID will be blank in the listview - tipping you off that this is bogus.
Just be aware of this situation and add the attributes described in the cause section above to be sure of what you are seeing.