Liquisys M CPM223/253 Diagnostics and troubleshooting
Endress+Hauser 83
7.3 Process specific errors
Use the following table to localize and rectify any errors occurring.
Errors Possible cause Tests and/or remedial measures Tools, spare parts
Device cannot be
operated, display value
9999
Operation locked
Press CAL and MINUS keys
simultaneously
See "Function of keys" section.
Measuring chain zero-
point cannot be adjusted
Reference system toxified Test with new sensor pH/ORP sensor
Diaphragm clogged Clean or grind down diaphragm
HCl 3 %, use file (only file in one
direction)
Measuring line open
Short-circuit pH input on instrument
display pH 7
Sensor asymmetry voltage too high
Clean diaphragm or test with another
sensor
HCl 3 %, use file (only file in one
direction); sensor
Potential matching (PA/PM)
transmitter wrong medium
Asymm.: no PM or PM at PE
Symm.: PM connection mandatory
See "Electrode installation and measuring
cable connection" section
No or creeping change of
display
Sensor contaminated Clean sensor. See "Cleaning pH/ORP electrodes" section.
Sensor ageing Replace sensor. New sensor
Sensor defective (reference lead) Replace sensor. New sensor
No internal buffer
Check KCl supply (0.8 bar (11.6 psi)
above medium pressure).
KCl (CPY 4-x)
Measuring chain slope
not adjustable/slope too
small
No high-impedance connection
(moisture, dirt)
Check cable, plug connector and junction
boxes.
pH simulator, insulation, see "Checking
the connecting lines and boxes" section
Device input defective Check device directly. pH simulator
Sensor ageing Renew sensor. pH sensor
Measuring chain slope
not adjustable/no slope
Hair-line crack in the glass
membrane
Renew sensor. pH sensor
No high-impedance connection
(moisture, dirt)
Check cable, plug connector and junction
boxes.
pH simulator, insulation, see "Checking
the connecting lines and boxes" section
Permanent, incorrect
measured value
Sensor not immersing or protection
cap not removed
Check installation position, remove
protection cap.
Air cushion in assembly Check assembly and orientation.
Ground connection at or in device
Perform test measurement in insulated
vessel, poss. with buffer solution.
Plastic vessel, buffer solutions
Hair-line crack in the glass
membrane
Renew sensor. pH sensor
Impermissible device operating
status (no reaction to key actuation)
Switch device off and then on again.
EMC problem: if this persists, check the
grounding, screens and line routing or
have checked by Endress+Hauser Service.
Incorrect temperature
value
Incorrect sensor connection Check connections using wiring diagram.
Wiring diagram "Electrical connection"
section
Measuring cable defective
Check cables for interruptions/short-
circuit/shunt.
Ohmmeter
Incorrect sensor type
Set type of temperature sensor at the
device (field B1).
Glass electrode: Pt 100
ISFET: Pt 1000
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