What to do if my HART 275 Cell Phone has no communication with field device?
- JJulie DonovanJul 27, 2025
If your HART Cell Phone isn't communicating with the field device, there could be several reasons. First, check that there is at least 4mA and 12V DC at the field device terminals, because there may be insufficient loop current and voltage. Another possible cause is insufficient loop resistance at the HART frequencies, so add an additional 250 ohm resistor in series in the loop. Place the HART Communicator leads across the resistor and verify if communication has been restored. Also, the field device may be set to a HART address other than zero (multi-drop mode), so change 275 mode to digital polling.