BACnet Bus Communications Status Objects for MS/TP Network Monitoring
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Solution Overview
Problem
Existing building automation and control systems face challenges in efficiently monitoring communication status across BACnet networks, particularly in large and complex systems, where bandwidth usage becomes a concern due to the need for frequent device pinging to detect failures, especially in MS/TP communications buses.
Innovation Solution
The implementation of proprietary BACnet objects, such as the Bus Communications Status Server and Client objects, which expose and monitor the communication status of MS/TP devices as a BACnet OCTET STRING value, allowing for change of value (COV) notifications without the need for continuous pinging, thereby reducing bandwidth usage and enabling prompt failure detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic pinging of all system components is performed to detect communication failures, then failure detection capability is improved, but communications bandwidth consumption increases substantially
Solution Approach 1:
The system performs preliminary actions by having devices proactively report their communication status and operational state at predetermined intervals without waiting for ping requests. This allows the master device to maintain an updated view of system health without consuming excessive bandwidth through continuous polling.
Solution Approach 2:
Instead of the master device actively pinging slave devices to check status (traditional polling), the invention inverts the approach by having slave devices autonomously report their status to the master. This reversal eliminates the need for continuous outgoing ping requests while maintaining reliable failure detection.
2Loss of time
If high-frequency pinging is used to satisfy fire control system requirements, then failure notification time is reduced, but bandwidth availability decreases
Solution Approach 1:
The system implements periodic action by having slave devices report their status at predetermined intervals rather than through continuous or high-frequency pinging. This periodic self-reporting mechanism satisfies fire control system requirements for timely failure notification while maintaining efficient bandwidth utilization through structured, interval-based communications.
3Reliability
If continuous monitoring of all devices is implemented, then system reliability is improved, but device complexity increases
Solution Approach 1:
The monitoring system implements self-service by having each slave device autonomously track and report its own communication status and operational state. This eliminates the need for complex centralized monitoring logic that would require the master device to manage individual monitoring of each slave, thereby improving reliability through comprehensive status tracking while reducing overall system complexity.
Data Source
AI summary
BACnet objects and methods for efficiently monitoring the communication status of networks and devices in a building automation and control system are presented. A pair of bus communication status objects, including a server object and a client object, provide the communication status of an MS/TP network as an OCTET String transmitted only upon a change of value (COV) of the communication status of a device on the network. Individual devices may be monitored with a device communication status object, in conjunction with or apart from the bus communication status objects. For MS/TP devices, automatic configuration and monitoring in a controller is provided. For other devices, a user interface is provided through a graphical tool to allow configuration to specify the desired device and/or network for monitoring.