Ace the 2026 HART Protocol & 4–20 mA Loop Challenge – Master the Fundamentals!

HART sends digital data by riding it on top of the 4-20 mA analog loop using two frequencies (FSK). The digital channel uses tones around 1 kHz and 2 kHz, and the data rate is 1200 baud. This rate was chosen to fit within the loop’s bandwidth and keep the analog signal clean over typical wiring and noise conditions. Higher speeds would require more bandwidth and could distort the analog signal, while slower speeds would be unnecessarily limiting. So, on the same loop, the standard baud rate for HART is 1200 baud.