AAC20 - BACnet MS/TP - Communication between 2 AAC20 controllers
The following article tells how to connect 2 AAC20 controllers together using RS485 bus and BACnet MS/TP protocol.
To integrate, first install the iSMA_BACnet and iSMA_BACnetMSTPMaster kits on both controllers.
Fig. 1 Basic list of kits required to connect 2 AAC20 controllers with the BACnet MS/TP protocol
Once the controllers are ready, proceed to edit the application. In both controllers, add BACnetNetwork, and LocalDevice and RemoteMSTPNetwork under it.
Fig. 2 Configuration of both controllers after adding basic BACnet components
Next, add and address the local points of both controllers (or at least one of them), for presentation purposes one point per controller was created:
Pressure (AV:0),
Setpoint (AV:0).
In the next step, configure the LocalDevice component for both cases - within one network, set unique values for the following slots:
Device Name,
Object Identifier.
The next step will be to configure the RemoteMSTPNetwork component; for the following slots, set the values described next:
Enabled - true,
Baud Rate - the same for all devices on the bus,
Mac Address - unique for each device connected to the RS485 bus.
Then, navigate to the RemoteMSTPNetwork component of one of the devices and invoke the discover action - a search of the RS485 bus will be initiated to find client devices operating over the BACnet MS/TP protocol. The result of the search will be placed in the Discove folder
Fig. 3 Searching results of one AAC20 controller in another
Selected devices should be marked and moved directly under the RemoteMSTPNetwork component, and the Discove folder should be deleted.
In the next step, turn on the searched device, and its basic information will be automatically loaded and displayed:
Fig. 4 The BACnet device moved to a correct location, switched on and with basic data loaded
In the next step, manually add the counter device points from the iSMA_BACnetMSTPMaster palette, address and enable.
Object Name will be loaded automatically, and after changing this value in one controller, the new value, will be visible in the other controller.
Fig. 5 Values overwritten from the controller 1 level
