Siemens SITRANS F series Operating Instructions Manual page 90

Diagnosing and troubleshooting
9.1 Unexpected behavior
Symptoms Diagnostics
Flow not stable
•
•
•
•
Device displays nega- -
tive flow
Pulse/frequency out- Error "P/F too high" is pending
put does not work (menu 2.1)
Device displays 0
flow.
Device status: "OK"
LCD display dark or
partly dark (missing
characters)
88
Error "Measurement path
error" is pending (menu 2.1)
Gain or the active paths > 250
Low or no signal return
Error counters are not equal
to 0.
Cause
Air bubbles or particles
of any kind disturbing
the measurement
Cable partly connected
Ultrasonic echoes
Sensor cables incor-
rectly connected
Wrong setting of meas-
urement direction
Internal electrical failure
(open circuit, short
circuit etc.)
Pulse/pause or fre-
quency out of range
Process flow value
•
is very low com-
pared with the low
flow cut-off limit of
the device
Sensor cables mis-
•
matched
Internal electrical failure
(open circuit, short
circuit etc.)
SITRANS F Ultrasonic flowmeters FST030 (Modbus)
Operating Instructions, 08/2017, A5E37367739-AC
Remedy
Make sure that the pipe line is venti-
lated and that the concentration of
particles is limited to a level at which
normal measurement with the meter
is possible.
Make sure that the sensor cables
are connected in the transmitter and
in the sensors.
Check the connection of the cable
grounding shield.
Make sure that the shield and cen-
ter pin is connected inside the sen-
sor top.
Make sure that the entered path
lengths correspond to the meas-
urement report.
Make sure that the sensor ca-
•
bles are connected correctly:
– 1A → 1A
– 1B → 1B
– 2A → 2A
– 2B → 2B
Change flow direction
•
Make sure that the setting of menu
3.1.5.1 is "+ Direction"
Start simulation on the
pulse/frequency output via menu
2.4. The frequency measuring in-
strument is coupled directly on the
terminals.
Adjust pulse or frequency output
settings (menu 4.2)
For testing, check the low flow cut
off (menu 3.1.6) is set to 0.
Turn off power. Check the connec-
tions for the power supply PCBA
and the flat cable for the display
module. Start display test (menu
2.3.2.) in case of partly dark display.