KROHNE BM 70 M - Manual (Page 69)

BM 70 M 69
Group DA: Display and signal output
No.
Fault / Symptom Cause Corrective action
DA17 Display and signal
output go suddenly
to "zero" or block
distance limit when
tank continuously
topped up. Level located in range of
block distance in front of
antenna, see Fct. 3.1.2 in
Sect. 8.6.3. Avoid this operating condition or,
if empty spectrum (Fct. 3.5.2) is
sufficiently good, reduce block
distance (Fct. 3.1.2) as
described in Sect.8.6.3.
Group M: Markers 1-6 & in display
No.
Fault / Symptom Cause Corrective action
M1 markers 1-5  (one
or several) ON.
Reference(s) to possible
faulty measurements. See Sect. 8.8 for significance of
markers and elimination of
possible faults.
M2 marker 2  ON for
long periods or
permanently.
Note: very strong reflection
signal (e.g. measurement in
the stilling well). Not important if measured value
is correct.
M3 marker 6  ON. Digital input is activated,
measurements suspended
(frozen). Deactivate digital input, see
Sect. 4.8.
Device located in block
distance detection range. Check conditions for block
distance detection, see Sect.
8.6.14.
M4 markers 3 and 4 
ON.
Level indicator is
"zero".
This is a status display and
not an error. This usually
occurs on tanks with dished
bottom, when the tank is
empty, after the BM 70 M
has been switched on or
after a new empty spectrum
has been recorded. Fill tank!
Group S: Switching output
No.
Fault / Symptom Cause Corrective action
S1 Switching output
does not operate at
the desired limit value
(threshold) or does
so in the wrong mode
(opens/closes).
Setting of switching function
is incorrect. Set switching output correctly as
described in Sect. 8.6.17 (Fct.
3.6.1 - 3.6.4).
S2 Switching output
does not operate.
Switching output defective. Check switching output as
described in Sect. 8.7.4:
- Test OK: check setting and
receiver instruments.
- Test reveals faults: switching
output defective. Consult
KROHNE Service or replace
BM 70 M signal converter as
described in Sect. 7.2.