Problem writing to third party BACnet device point from within bCX PE program


A PE program is configured to write to the Present Value of a point in a third party IP level device, the program is enabled/active but the value in the 3rd party device is not taking on the new value. 

Product Line

Andover Continuum




3rd party IP level BACnet device


Wireshark capture shows the bCX trying to locate the 3rd party device via directed who-is message, the capture also shows that the bCX is directing the who-is message to the wrong sub-network.

The reason for the above is an improperly configured subnet mask in the bCX


The bCX will calculate the subnet address by taking its own IP address and ANDing it with the subnet mask, if the subnet mask is incorrect the calculation will render an incorrect address.

Configure the bCX subnet mask correctly using the controller's web page configuration.