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Reference Manual
00809-0100-4021, Rev DA
November 2004
3-35
Rosemount 3144P
HART
TROUBLESHOOTING
HART / 4–20 mA If a malfunction is suspected despite the absence of a diagnostics message
on the 375 Field Communicator display, follow the procedures described in
Table 3-1 to verify that transmitter hardware and process connections are in
good working order. Under each of four major symptoms, specific suggestions
are offered for solving problems. Always deal with the most likely and
easiest-to-check conditions first.
Advanced troubleshooting information is available in Table 3-2 on page 3-36.
Table 3-1. HART / 4–20 mA Basic Troubleshooting
Symptom Potential Source Corrective Action
Transmitter Does Not
Communicate with 375 Field
Communicator
Loop Wiring
• Check the revision level of the transmitter device descriptors (DDs) stored in
your communicator. The communicator should report Dev v3, DD v2
(improved), or Dev v2, DD v1 (previous). Contact Emerson Process
Management Customer Central for assistance.
• Check for a minimum of 250 ohms resistance between the power supply and
375 Field Communicator connection.
• Check for adequate voltage to the transmitter. If a 375 Field Communicator is
connected and 250 ohms resistance is properly in the loop, then the transmitter
requires a minimum of 12.0 V at the terminals to operate (over entire 3.90 to
20.5 mA operating range), and 17.5 V minimum to communicate digitally.
• Check for intermittent shorts, open circuits, and multiple grounds.
High Output
Sensor Input
Failure or Connection
• Connect a 375 Field Communicator and enter the transmitter test mode to
isolate a sensor failure.
• Check for a sensor open circuit.
• Check if the process variable is out of range.
Loop Wiring
• Check for dirty or defective terminals, interconnecting pins, or receptacles.
Power Supply
• Check the output voltage of the power supply at the transmitter terminals. It
should be 12.0 to 42.4 V dc (over entire 3.90 to 20.5 mA operating range).
Electronics Module
• Connect a 375 Field Communicator and enter the transmitter test mode to
isolate module failure.
• Connect a 375 Field Communicator and check the sensor limits to ensure
calibration adjustments are within the sensor range.
Erratic Output
Loop wiring
• Check for adequate voltage to the transmitter. It should be 12.0 to 42.4 V dc at
the transmitter terminals (over entire 3.90 to 20.5 mA operating range).
• Check for intermittent shorts, open circuits, and multiple grounds.
• Connect a 375 Field Communicator and enter the loop test mode to generate
signals of 4 mA, 20 mA, and user-selected values.
Electronics Module
• Connect a 375 Field Communicator and enter the transmitter test mode to
isolate module failure.
Low Output or No Output
Sensor Element • Connect a 375 Field Communicator and enter the transmitter test mode to
isolate a sensor failure.
• Check if the process variable is out of range.
Loop Wiring • Check for adequate voltage to the transmitter. It should be 12.0 to 42.4 V dc
(over entire 3.90 to 20.5 mA operating range).
• Check for shorts and multiple grounds.
• Check for proper polarity at the signal terminal.
• Check the loop impedance.
• Connect a 375 Field Communicator and enter the loop test mode.
• Check wire insulation to detect possible shorts to ground.
Electronics Module • Connect a 375 Field Communicator and check the sensor limits to ensure
calibration adjustments are within the sensor range.
• Connect a 375 Field Communicator and enter the transmitter test mode to
isolate an electronics
module failure.