Which service is required to be supported by all BACnet devices?

The read-property service is a fundamental requirement for all BACnet devices because it allows clients to retrieve the current values of properties defined in the devices. This service is essential for monitoring and managing devices in a building automation system. Without the ability to read properties, a client would lack a key means to check the status and configuration of the devices on the network, which is critical for system operation and troubleshooting.

In a BACnet network, each device can expose multiple objects and their properties. The read-property service enables the retrieval of information such as temperature, humidity, and operational status, which are vital for making informed decisions in automated environments.

The other services mentioned, such as write-property, update-property, and command-property, may enhance the functionality of BACnet devices, but they are not universally required. Not all BACnet devices need to support writing to properties or handling commands; their primary role could simply be to provide information. Thus, while these services contribute to a more dynamic interaction between devices, the read-property service remains a foundational aspect of BACnet compliance.