Diagnostics And Servicing; Maintenance; Diagnosis Memory - Siemens SITRANS LG250 Operating Instructions Manual

Measured value memory
Event memory
PBD-51041387

10 Diagnostics and servicing

10.1 Maintenance

If the instrument is used correctly, no maintenance is required in
normal operation.
When used in safety-instrumented systems (SIS), the safety function
must be carried out on the instrument in regular time intervals by
means of a proof test.
Hence possible undetected, dangerous failure can be identified.
The operator's responsibility to select the kind of test. The time inter-
vals depend on the used PFD
During the function test, the safety function must be treated as unsafe.
Keep in mind that the function test influences downstream connected
devices.
If one of the tests proves negative, the entire measuring system must
be switched out of service and the process held in a safe state by
means of other measures.
You can find detailed information on the proof test in the Safety
Manual (SIL).

10.2 Diagnosis memory

The instrument has several memories which are available for
diagnostic purposes. The data remain there even in case of voltage
interruption.
Up to 100,000 measured values can be stored in the sensor in a ring
memory. Each entry contains date/time as well as the respective
measured value. Storable values are for example:
•
Distance
•
Filling height
•
Percentage value
•
Lin. percent
•
Scaled
•
Current value
•
Meas. certainty
•
Electronics temperature
When the instrument is shipped, the measured value memory is
active and stores distance, measurement certainty and electronics
temperature every 3 minutes.
In "Extended adjustment" you can select the respective measured
values.
The requested values and recording conditions are set via a PC with
PACTware/DTM or the control system with EDD. Data are thus read
out and also reset.
Up to 500 events are automatically stored with a time stamp in the
sensor (non-deletable). Each entry contains date/time, event type,
event description and value. Event types are for example:
SITRANS LG250 - Operating Instructions
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