Maintenance and Troubleshooting
December 2009
7-17
Table 7-2. Instrument Troubleshooting (Continued)
Symptom ActionPossible Cause
6. Block dynamic parameters do not
update
6.a Block actual mode is Out of Service 6.a Change the block target mode to an operational
mode (see FOUNDATION fieldbus Communication,
Appendix D and host system documentation).
7. Transducer block Setpoint
(FINAL_VALUE [13]) is not being
automatically updated from the AO
block.
7.a Transducer block mode in not Auto. 7.a Change transducer block mode to Auto.
7.b AO block is not active. 7.b Change Outblock Selection to AO Control.
8. Transducer block setpoint
Setpoint(D) (SETPOINT_D [32]) is not
being automatically updated from the
DO block.
8.a Transducer block mode is not Auto. 8.a Change transducer block mode to Auto.
8.b DO block is not active. 8.b Change Outblock Selection to DO Control.
9. Valve does not move when the set
point is changed
9.a A function block actual mode is Out of Service or
Transducer Block Actual mode is Out of Service or
Manual.
9.a1 Change the target mode to an operational mode
(see FOUNDATION fieldbus Communication,
Appendix D and host system documentation).
9.a2 Verify that the correct block (AO or DO) is
configured in Feature Select in the resource block.
Only the selected out block is able to set the
transducer setpoint and move the valve.
9.b Pneumatic connections are incorrect or supply
pressure is incorrect
9.b Check pneumatic connections and supply
pressure. Be sure supply pressure regulator is set
correctly (see Pressure Connections on page 2-19 of
the Installation Section).
9.c Instrument is in fault state. 9.c Set Clear FState to Clear (Refer to Fault State on
page 4-5 of the Detailed Setup / Blocks Section, or
host system documentation).
9.d The valve has failed. 9.d Apply a pneumatic pressure to the valve actuator
and check valve action.
9.e The I/P converter or relay has failed. 9.e Replace the I/P converter or relay (see Replacing
the I/P Converter on page 7-7).
10. Valve does not stroke from 0 to
100% with set point change
10.a Insufficient supply pressure or leak in pneumatic
connections.
10.a Check supply pressure and supply pressure
regulator setting. Check for leaks around pneumatic
connections.
10.b Setpoint may be limited. 10.b Check the AO Block values of SP_HI_LIMIT
and SP_LO_LIMIT (see page 4-77 of the Detailed
Setup / Blocks Section or host system
documentation).
11. Deviation between set point and
actual valve position remains.
11.a Digital valve controller output is in cutoff. 11.a Check values for Travel Cutoff High and Travel
Cutoff Low (see page 4-25 of the Detailed Setup /
Blocks Section or host system documentation).
11.b Digital valve controller is not calibrated correctly 11.b Perform Auto or Manual Travel Calibration
(Travel Calibration on page 5-2.)
11.c Incorrect turning. Tuning that is too conservative
will result in excess error.
11.c Perform Stabilizing/Optimize Valve Response
procedure to adjust tuning and stabilize/optimize
valve response (see Stabilize/Optimize on page
4-23).
12. The valve cycles, does not stay on
set point.
12.a Large amount of packing friction.
12.a1 Perform Stabilizing/Optimize Valve Response
procedure to adjust tuning and stabilize/optimize
valve response (see Stabilize/Optimize on page
4-23).
12.a2 Use a larger size actuator.
13. Valve responds too slowly.
13.a Insufficient instrument gain. 13.a Perform Stabilize/Optimize Valve Response
procedure to adjust tuning and stabilize valve
response (see Stabilize/Optimize on page 4-23).
13.b I/P converter input filter clogged or air blockage in
I/P ass’y nozzle block.
13.b1 Replace I/P converter filter (see Replacing the
I/P Filter on page 7-6).
13.b2 Replace I/P converter (see Replacing the I/P
Converter on page 7-7).
13.c O-ring(s) between I/P converter missing or hard
and flattened losing seal.
13.c Replace O-ring(s) (refer to the I/P Converter
section on page 7-6).
−Continued−
7
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