By Eamonn Ryan derived from a SAIRAC Johannesburg Centre TechTalk on 12 February
In the February SAIRAC Johannesburg Centre TechTalk presented by Robert Fox, SAIRAC national president with over 31 years of experience, he discusses the critical differences between open-source and proprietary solutions for HVAC systems. As a senior cost and design estimator at Club Refrigeration, Fox has extensive insight into both the challenges and benefits associated with each system. This is Part 2 of a ten-part series.
Robert Fox, SAIRAC national president. © RACA Journal
Fox clarifies that open-source and proprietary systems can coexist, but their compatibility depends on the specific application. Some use cases may benefit from the flexibility of open-source software, while others, especially those in regulated industries, might require the robustness of proprietary systems. The decision to use one over the other hinges on factors such as regulatory requirements, system complexity and liability concerns.
One of the key technical aspects of the talk focuses on the programming of HVAC controllers using Python. Fox shared insights into a library called BAC0, a tool that simplifies the development and customisation of HVAC control systems. While many may not be familiar with BAC0, Fox introduces it as a powerful library that allows HVAC professionals to write custom code for controlling HVAC systems, providing greater flexibility and precision.
Python, known for its ease of use, offers HVAC engineers the ability to create tailored solutions for specific needs. However, Fox stresses that programming HVAC controllers is not a simple task. Thorough testing and a deep understanding of communication protocols, such as LonTalk/Lonwork, BACnet and Modbus – which is now progressing to BACnet/IP – are crucial for ensuring the reliability of these systems. These protocols enable communication between devices within an HVAC system, and any mistake in programming could lead to system failures or inefficient operation.
Fox begins by explaining the variety of communication protocols that have been developed over the years to facilitate communication between HVAC controllers and devices. These protocols include:
- Modbus (RS-232, RS-485, TCP/IP): One of the most common communication standards in industrial automation, Modbus is an open-source, royalty-free protocol widely used to connect industrial devices via serial ports or over TCP/IP networks. Its client-server model allows devices to communicate easily, making it particularly popular in IoT and industrial applications.
- LonWorks: Developed in the late 1980s, LonWorks is an open standard that enables devices to communicate over various media types such as twisted pair wires, power lines, fibre optics and wireless networks. It provides flexibility in building control applications and is still relevant in automation today.
- BACnet: First introduced in the mid-1980s by ASHRAE (American Society of Heating, Refrigerationg and Air-Conditioning Engineers), BACnet (Building Automation Control Network) is an open communication protocol specifically designed for building automation. It allows for interoperability between devices from different manufacturers, enabling centralised control and monitoring of HVAC systems.
