In a HART network, what triggers the master to poll a device for data?

• A. The master issues a command addressed to a specific device; polling can be scheduled or on-demand
• B. The device polls the master
• C. The master broadcasts to all devices
• D. The network automatically responds

Answer: (A)

In a HART network, the master controls the data flow by initiating communication. It polls data by sending a command specifically addressed to one device on the loop. This polling can be scheduled ahead of time or started on demand when data is needed. The addressed device then replies with its measurement, status, or diagnostic data. The device does not initiate communication, and the network does not generate data automatically without a master request. Broadcast to all devices isn’t the usual method for retrieving a particular device’s data, and there isn’t an autonomous network response.