Burst-Mode is optional for a HART products but is strongly recommended.
HART Burst-Mode supports the publishing of cyclical process data using "Burst" messaging. In this mode, a device is instructed to publish the response to a command continuously without any further Master or Host action.
If a Field Device supports Burst-Mode then all of Commands 103-105 and Commands 107-109 must be implemented. Furthermore, devices implementing Burst-Mode must support at least 3 Burst Messages. Existing, legacy Field Devices updated from HART 5 are allowed to support only one Burst Message.