| Overview
As part of enhancing the interoperability capabilities of the ClimaVision Building Management System, support for BACnet MSTP (Master-Slave/Token-Passing) has been added to the CCU. While the CCU already supports BACnet/IP communication, MSTP support enables seamless integration with a wide range of MSTP-based field devices, sensors, controllers, and third-party equipment commonly used in legacy and modern building automation environments.
With this enhancement, the CCU can now read data points from external BACnet MSTP devices and optionally write control values as part of its automation logic.
| Why BACnet MSTP on the CCU?
The CCU is positioned as a complete IoT-based Building Management Controller. For it to function as a supervisory device within mixed-vendor environments, it must:
Communicate with third-party controllers and devices
Fetch real-time values for monitoring
Write data for control operations and algorithm execution
Integrate legacy systems that operate on MSTP networks
By introducing MSTP support, the CCU can now act as a BACnet supervisor/master for devices that do not support BACnet/IP.
| What is BACnet MSTP?
BACnet MSTP (Master-Slave/Token-Passing) is a serial communication protocol typically operating over RS-485. In MSTP networks:
Devices are assigned MAC addresses
A token circulates among master devices
Only the device holding the token is allowed to initiate communication
For ClimaVision's integration:
The CCU operates as the MSTP Master, initiating all read and write requests.
The external MSTP devices (e.g., HyperStat MSTP) operate as slave or subordinate devices, responding only when addressed.
| MSTP Dongle Setup via USB Manager
To begin MSTP communication, the user configures the MSTP interface through the USB Manager on the CCU.
Identify the MSTP USB Dongle
Navigate to USB Manager
Locate the connected MSTP dongle
Select the dongle and choose BACnet MSTP as its protocol
Enter MSTP Configuration
Enter standard BACnet MSTP supervisor settings:
Baud rate
MAC address of the CCU (as master)
Max masters
Max info frames
Network ID
Once configuration is complete,
Click Initialize.
The dongle status changes from Disabled → Initialized, indicating successful setup (same behavior as BACnet/IP initialization).
| Device Pairing Workflow
Once the MSTP network interface is initialized, devices can be paired similarly to wireless zones.
Select Device Type
Navigate to the zone pairing section
Choose Custom Equipment
Select BACnet Equipment from the available options
Select Device Model
Choose the appropriate MSTP-enabled model
Example: HyperStat MSTP
Select Communication Type
Although the CCU does not inherently know it is a ClimaVision device:
The UI displays both MSTP and IP options
Select MSTP
Choose Device Role
BACnet MSTP auto assigns MAC addresses based on device type:
Master devices: MAC 1–127
Slave devices: MAC 128–254
Device Discovery
After selecting the role:
The CCU scans the MSTP network
All detected MSTP devices appear in the list
Example: HyperStat found at MAC Address 4
Once selected and saved, the device is fully paired with the CCU.
| Data Visibility and Control
After pairing:
A dynamic Zones Page is created for the MSTP device.
The page updates in real time as data changes on the MSTP network.
Typical real-time parameters include:
Occupancy (Open/Close or 1/0)
Temperatures
Setpoints
Modes
Equipment states
Users can:
View live sensor readings
Write values like heating/cooling setpoints
Observe immediate feedback on the UI
The experience is identical to other ClimaVision device integrations but via MSTP.
The BACnet MSTP module transforms the CCU into a versatile supervisory controller capable of integrating heterogeneous building automation systems. The workflow—USB Manager setup, MSTP initialization, device discovery, and real-time data interaction—provides a robust and user-friendly method for MSTP deployments.
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