6.3 Hardware Diagnostics
If there is a failure dispite a diagnostic message on the HHT, Table
6.1 can help troubleshoot the problem.
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Symptom
Transmitter does not
Communicate with HART
®
Communicator
High Output
Erratic Output
Low Output or No Output
Potential Source
Loop Wiring
Sensor Input Failure
L
oop Wiring
Power Supply
Electronics Module
Loop Wiring
Electronics Module
Sensor Element
Loop Wiring
Electronics Module
Corrective Action
• Check for a 250-550 ohms resistance
between the power supply and HHT.
• Check for adequate voltage to the transmitter
(the transmitter requires 11.9 ~ 45 Vdc).
• Check for intermittent shorts, open circuits, and
multiple grounds.
• Connect HHT and enter the transmitter test
mode to isolate a sensor failure.
• Check for dirty or defective terminals,
interconnecting pins, or receptacles.
• Check the output voltage of the power supply
at the transmitter terminals. It should be 11.9
to 45 Vdc.
• Connect HHT and enter the transmitter test
mode to isolate module failure. Check the
sensor limits to ensure the calibration
adjustments are within the sensor range.
• Check the output voltage of the power supply
at the transmitter terminals. It should be 11.9
to 45 Vdc.
• Check for intermittent shorts, open circuits, and
multiple grounds.
• Check for proper polarity at the signal terminals.
• Connect HHT and enter the transmitter test
mode to isolate an electronics mode failure.
• Connect HHT and enter the transmitter test
mode to isolate a sensor failure.
• Is the PV out of range.
• Check for adequate voltage to the transmitter
(the transmitter requires 11.9 ~ 45 Vdc).
• Check for intermittent shorts, open circuits, and
multiple grounds.
• Check polarity of signal terminal
• Check the loop impedance.
• Connect HHT and check the sensor limits to
ensure calibration adjustments are within the
sensor range.
Table 6.1 Troubleshooting
