Fisher FIELDVUE DLC3010 Instruction Manual page 73

Instruction Manual
D102748X012
Table 6‐1. Troubleshooting
Symptom Potential Source
Loop Wiring
Analog Output is within valid
range but Instrument does
not communicate with Field
Communicator
Terminal Box
Electronics Module
Transducer Module
Loop Wiring
Output ` 0 mA
Terminal Box
Electronics Module
Transducer Module
Alarm Condition
Fixed Output ` 3.7 mA
(Fail‐low setting)
Fixed Output = 3.8 mA Low Saturation
Fixed Output = 20.5 mA High Saturation
Alarm Condition
Fixed Output ` 22.5 mA
(Fail‐high setting)
Loop Wiring
Terminal Box
Fixed Output > 22.5 mA
Electronics Module
Output is within 4-20 mA
range, but does not track
displayed PV value (e.g.,
a) gain error,
Electronics Module
b) low saturation occurs at a
value higher than 3.8 mA,
c) high saturation occurs at a
value lower than 20.5 mA)
Sensor
Transducer Module
Output Drifting while at
fixed process input.
Electronics Module
Configuration Data
Erratic Output Loop Wiring
Loop Wiring
Scrambled or erratic Display
LCD Assy
on LCD
Electronics Module
1. Check resistance between the power supply and the Field Communicator connection. The net resistance in the
loop must be between 230 and 1100 Ohms for HART communication.
2. Check for adequate voltage to the digital level controller. Refer to figure 2‐10 for requirements. Some models
of battery‐operated field calibrators do not have sufficient compliance voltage to operate a DLC3010 over the
entire output current range.
3. Check for excessive capacitance in the field wiring. (Isolate the instrument from field wiring and try to
communicate locally.)
4. If the terminal box does not have a 4‐digit date‐code sticker inside the lower lip, it may have developed a high
internal resistance. Try a new terminal box.
5. Swap the electronics module with a known good part.
6. If the electronics module and terminal box work on a known good transducer module, replace the old
transducer module.
7. Check for open circuits.
8. Check for proper polarity at the signal terminals.
— See item 2. above.
9. Check resistance between "Loop+" and "T" terminals of terminal box. If greater than 1.1 Ohm, the internal
sense resistor may be damaged. An external jumper may be added for a temporary repair. Replace terminal box
and avoid applying loop voltage across "T" and "Loop+" for long term solution.
— See item 4. above
— See item 5. above.
— See item 6. above.
Connect the Field Communicator and:
10. Select LCD Test (3-3-1-1)to isolate a module failure.
11. Check PV against Hi‐Hi and Lo‐Lo alarm thresholds and PV alarm deadband setting, if these alarms are
enabled.
Connect the Field Communicator and:
12. Check the PV against the upper and lower range values. Check actual process condition and calibration
adjustments.
Connect the Field Communicator and:
— see item 12. above.
Connect the Field Communicator and:
— see items 10. and 11. above.
13. Check for short circuits.
14. Remove terminal box from the instrument, and apply 24 Volts between Loop+ and Loop- terminals, (with a
series resistance of approximately 1200 Ohms to protect power supply). If any current flows, replace terminal box.
— See item 5. above.
Connect the Field Communicator and:
15. Run Loop diagnostic test (3-3-1-1) [(3-3-1-2) if LCD Configuration is installed]. If the forced output does not
track commands, attempt Scaled D/A Trim procedure (2‐5-2-2-1). If D/A calibration cannot be restored, replace
Electronics Module.
16. Check torque tube spring rate change versus process temperature per figure 1‐2. Use appropriate material for
process temperature. Pre‐compensate the calibration for target process condition.
Connect the Field Communicator and:
17. Check Instrument Temperature (3‐2-4) against an independent measurement of DLC3010 temperature.
a) If inaccurate, trim the instrument temperature measurement (2-5-2-1-1) to improve ambient temperature
compensation performance.
b) If Instrument Temperature value is extreme, replace transducer module.
Connect the Field Communicator and:
18. Run Loop diagnostic test (3-3-1-1) [(3-3-1-2) if LCD Configuration is installed]). Leave instrument in fixed
current mode at 12 mA command and observe analog output variation with ambient temperature. If drift exceeds
specifications replace electronics module.
Connect the Field Communicator and:
19. Check stored Specific Gravity values (2-2-3-1) against independent measurement of process density. If process
SG has changed from calibration values, correct configuration data to match process
If output current enters a limit cycle between zero and a value within the 4-20 mA range when level reaches some
arbitrary upper threshold,
20. Check for excessive loop resistance or low compliance voltage. (See items 2. and 4. above.)
—see item 20. above. (Insufficient voltage to operate display)
21. Swap LCD Assy with known good part.
22. Connector solder joint failure in electronics module. Replace module.
Maintenance & Troubleshooting
Corrective Action
October 2014
73