Endress+Hauser Liquisys M CUM253 - Page 79

Liquisys M CUM223/253 Diagnostics and troubleshooting
Endress+Hauser 79
Controller/limit contact
does not work
Controller switched off Activate controller. See fields R2xx.
Controller in "Manual/Off" mode Choose "Auto" or "Manual/On" mode. Keyboard, REL-key
Pickup delay setting too long Disable or shorten pickup delay. See fields R2xx.
"Hold" function active “Automatic Hold” during calibration,
“Hold” input activated;
“Hold” via keyboard active.
See fields S2 to S4.
Controller/limit contact
works continuously
Controller in "Manual/On" mode Set controller to "Manual/Off" or "Auto". Keyboard, REL and AUTO keys
Dropout delay setting too long Shorten dropout delay. See field R2xx.
Control loop interruption Check measured value, current output,
actuators, chemical supply.
No turbidity current
output signal
Line open or short-circuited Disconnect line and measure directly on
instrument.
mA meter 0–20 mA
Total load in current loop excessive
(>500)
Disconnect line and measure line. Ohmmeter
Instrument with PROFIBUS PA/DP PA/DP instruments have no current
output.
Fixed current output
signal
Current simulation active Switch off simulation. See field O3 (2).
Impermissible operating state of
processor system
Switch instrument off and back on. EMC problem: check installation, screen,
grounding if problem persists.
Incorrect current output
signal
Incorrect current assignment Check current assignment: 0–20 mA or
4–20 mA?
Field O311
Total load in current loop excessive
(> 500 .)
Disconnect line and measure line. Ohmmeter
Current output table not
accepted
Value interval too small Select practical intervals.
No HART communication
No central HART module Verify by looking at nameplate:
HART = -xxx5xx and -xxx6xx.
Upgrade to LSCH-H1 / -H2.
No or wrong DD (device description) For further information see BA00208C/
07/en, “HART® - Field communication
with Liquisys M CxM223/253”.
HART interface missing
Instrument not registered with
HART server
Load too low (load > 230 
required)
HART receiver (e.g. FXA 191) not
connected via load but via power
supply
Incorrect device address (addr. = 0
for single operation, addr. > 0 for
multi-drop operation)
Line capacitance too high
Line interferences
Several devices set to same address Set addresses correctly. Communication not possible with several
devices set to same address.
Error Possible cause Tests and / or remedial measures Equipment, spare parts, personnel