Diagnostics and troubleshooting Liquisys M CPM223/253
84 Endress+Hauser
pH value in process wrong
No/incorrect temperature
compensation
ATC: activate function.
MTC: adjust process temperature.
Conductivity of medium too low Select pH sensor with liquid KCl. e.g. Ceraliquid CPS41
Flow too high Reduce flow or measure in a bypass.
Potential in medium
Poss. ground with or at PM pin
(connection PM/PE).
Problem occurs particularly in plastic
lines.
Sensor contaminated or assigned
Clean sensor (see "Cleaning pH/ORP
sensors" section).
For heavily contaminated media:
Use spray cleaning.
Measured value
fluctuations
Interference on measuring cable Connect cable as per wiring diagram. See "Electrical connection" section.
Interference on signal output line
Check line routing, lay line separately if
necessary.
Signal output and measuring input lines
Interference potential in medium Measure symmetrically (with PML).
Poss. ground medium with PM/PE
connection.
No potential matching (PA/PM) for
symmetrical input
Connect PM pin in assembly with devices
PA/PM.
Controller/limit contact
does not work
Controller switched off Activate controller.
See "Relay contact configuration" section
or fields R2xx.
Controller in operating mode
"Manual/off"
Select "Auto" or "Manual on" mode. Keyboard, REL key
Pick-up delay set too long Switch off or shorten pick-up delay time. See fields R2xx.
"Hold" function active
“Auto hold” for calibration,
“Hold” input activated,
“Hold” active via keyboard.
See fields S2 to S4.
Controller/limit contact
works constantly
Controller in operating mode
"Manual/on"
Set controller to "Manual/off" or "Auto". Keyboard, REL and AUTO keys
Drop-out delay set too long Reduce drop-out delay time. See fields R2xx.
Control circuit interrupted
Check measured value, current output or
relay contacts, adjusters, chemical
supply.
No pH/mV current output
signal
Line open or short-circuited
Disconnect line and measure directly at
the device.
mA meter 0–20 mA DC
Output defective See "Diagnosis" section.
Fixed pH/mV current
output signal
Current simulation active Switch off simulation. See field O2.
Impermissible processor system
operating status
Switch device off and then on again.
EMC problem: if it persists, check the
installation.
Incorrect current output
signal
Incorrect current assignment
Check current assignment:
0–20 mA or 4–20 mA?
Field O211
Overall burden in the current loop
too high (> 500 )
Disconnect output and measure directly
at the device.
mA meter for 0–20 mA DC
Current output table is
not accepted
Value distance too small Select practical distances.
No temperature output
signal
Device does not have a second
current output
Check version using nameplate, if
necessary, replace module LSCH-x1.
Module LSCH-x2,
See "Spare parts" section.
Device with PROFIBUS-PA
PA device does not have any current
output!
Chemoclean function not
available
No relay module (LSR1-x) installed
or only LSR1-2 available
Install LSR1-4 module.
The Chemoclean is enabled using the
release code supplied by E+H in the
Chemoclean retrofit kit.
Module LSR1-4, see "Spare parts" section.
Errors Possible cause Tests and/or remedial measures Tools, spare parts
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