Troubleshooting The 4-20 Ma/Hart Output - Emerson Rosemount 2140 Reference Manual

Service and troubleshooting
March 2022
7.3

Troubleshooting the 4-20 mA/HART Output

7.3.1 Device milliamp reading is zero
Recommended actions
7.3.2 Device is not communicating with handheld
communicator
Recommended actions
7.3.3 Device milliamp reading is too low or high
Recommended actions
7.3.4 Milliamp reading is erratic
Recommended actions
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1. Verify power is applied to signal terminals.
2. Verify power supply voltage is adequate at signal terminals.
3. Check power wires for reversed polarity.
4. Verify device and power supply are properly grounded.
5. Check for open diode across test terminal.
1. Verify power supply voltage is adequate at signal terminals.
2. Check load resistance (250 ohms minimum).
3. Check that power wires are connected to signal terminals and not test
terminals.
4. Verify clean DC Power to level detector (Max AC noise 0.2 volts peak to peak).
5. Verify the output is between 4 and 20 mA or saturation levels.
6. Have handheld communicator poll for all addresses.
1. Check the settings of the 4-20 mA range values.
2. Verify output is not in alarm condition.
3. Check that power wires are connected to the correct signal terminals.
4. Perform Calibrate Analog Out.
1. Verify power supply voltage is adequate at signal terminals.
2. Check for external electrical interference.
3. Verify device is properly grounded.
4. Verify shield for twisted pair is only grounded at one end.
Reference Manual
00809-0100-4140
Reference Manual