Issue
Considering changing the bCX MSTP BACnet MAC ID to an available value in the 1-127 range as indicated in the bCX web page configuration.
The online Help provides the following information on the setting.
BACnet MAC ID - Comm2 Identifies the MAC (Media Access Control) networking address of the controller on its MS/TP network, using integers ranging from 0 to 127.
The default address is 0 and it only necessary to change this value if the value has already been assigned to another device on the network.
Product Line
Andover Continuum
Environment
- bCX4040
- bCX4000
- b3 devices
- BACnet 3rd party device
Cause
BACnet MAC ID 0 (zero) on MSTP network already in use by third party device.
Resolution
Due to a limitation in the b3 devices the bCX's MSTP MAC ID should not be changed unless the bCX will only host third party devices on its MSTP (Comm2) and will NEVER be in a situation where MAC ID zero is available during a b3 learn operation.
The issue is that when ID zero is made available (by changing the default in the bCX) the LEARN process done on b3s will assign ID zero to one of the b3s, because of design constraints, a b3 will not operate correctly if assigned MAC id zero.
Product Support strongly recommends that if a third party device is using MAC ID zero on the MSTP, that the device be re-assigned a different ID in order to keep the bCX at its default value of MAC ID zero.
