What is the difference between polling and burst mode in HART?

What is the difference between polling and burst mode in HART?

• A. Polling is master-initiated data transfer; burst mode allows devices to periodically push data without a master request.
• B. Polling happens only at startup; burst mode never transmits data.
• C. Burst mode is a form of master-initiated polling at higher frequency.
• D. There is no difference; they are the same mechanism.

Answer: (B)

Polling is the master-initiated data transfer where the master asks a device for its data and the device replies. Burst mode is a special HART operation: once the master grants a burst window, the device can send a block of digital data autonomously within that window, often for many variables at a higher data rate. The master still controls when bursts happen, but during the burst the data flow is continuous and data-rich, rather than a single reply to each poll. So polling keeps you requesting one reading at a time in regular intervals, while burst mode lets devices push a bunch of readings quickly in a dedicated time window. Burst mode does transmit data; polling does not run out of data, it simply asks for it.

Polling is the master-initiated data transfer where the master asks a device for its data and the device replies. Burst mode is a special HART operation: once the master grants a burst window, the device can send a block of digital data autonomously within that window, often for many variables at a higher data rate. The master still controls when bursts happen, but during the burst the data flow is continuous and data-rich, rather than a single reply to each poll.

So polling keeps you requesting one reading at a time in regular intervals, while burst mode lets devices push a bunch of readings quickly in a dedicated time window. Burst mode does transmit data; polling does not run out of data, it simply asks for it.