Logix 3400MD Digital Positioner FCD LGENIM3404-00 – 9/09
50
15 Troubleshooting
Table XVIII: Troubleshooting
Failure Probable Cause Corrective Action
No LED is blinking
Voltage of supply source is not high enough Verify that voltage source can supply at least 9 V
Current draw incorrect
Verify current draw of device (23 mA) and that of other
devices on the loop aren’t pulling too much current
Erratic communications
Maximum cable length or cable impedance exceeded
Check cable conduction size, length and capacitance. Refer
to Section 6.4, “Cable Requirements”
Improper grounding Terminate and ground segment properly.
Interference with I.S. barrier Must use FF-compatible I.S. barrier
Host FB card not configured or connected correctly Check connections and configurations of card
Unit does not respond to Final
Value commands
Unit is in Auto mode Put in OOS mode
Error occurred during calibration
Check blink codes on positioner and correct
calibration error. Recalibrate
Valve position reading is not what
is expected
Positioner tubing backwards Re-tube the actuator
Stem position sensor mounting is off 180° Remount position sensor
Stroke not calibrated Perform RE-CAL
Tight shutoff is active Verify settings using PC or handheld software
Customer characterization or soft stops active Verify customer characterization and soft stops
Position is driven fully open or
closed and will not respond to
command
Stroke not calibrated Check DIP switch settings and calibrate valve stroke
Inner-loop hall sensor not connected Verify hardware connections
Wrong air action entered in software
Check ATO (Air-to-open) and ATC
(Air-to-close) settings. Recalibrate
Actuator tubing backward Verify ATO/ATC actuator tubing
Driver module Electro-pneumatic converter malfunctioning Replace driver module
Control parameter inner-loop offset is too high/low Adjust inner-loop offset and see if proper control resumes
Sticking or hunting operation of
the positioner
Contamination of the driver module
Check air supply for proper filtering and meeting ISA
specifications ISA-7.0.01. Check the spool valve for
contamination
Control tuning parameters not correct Adjust gain settings using local gain switch
Packing friction high
Enable the stability DIP switch on the local interface and
recalibrate. If problem persists, enable pressure control with
handheld communicator or SoftTools and recalibrate
Corroded or dirty spool valve Disassemble and clean spool valve
* Final Value Cutoff
NOTE: Refer to blink codes for self diagnostics of other errors. See document #VLAIM0046. Refer to Logix 3400/1400 Reference Manual for Fieldbus
related troubleshooting.
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