Endress+Hauser Fieldbus levelflex M FMP 40 Operating Instructions Manual page 99

Levelflex M FMP 40 with Foundation Fieldbus
Endress+Hauser
Output
The Levelflex is initially adjusted at the factory to the probe length ordered, so that in
most cases only the application parameters, that automatically adapt the device to the
measuring conditions, need to be entered. For models with current output, the factory
adjustment for zero point and span is F 4 mA and 20 mA, for digital outputs and the
display module 0 % and 100 %.
A linearisation function with max. 32 points, that is based on a manually or semi-
automatically input table, can be activated on-site or via remote operation. This function
enables, for example, the conversion of the level into units of volume or weight.
An evaluation of the measurement with the aid of the envelope curve
Typical curve shape
The following examples display typical curve shapes for a rope or rod probe in an empty
tank. For all probe types, a negative probe end signal is shown. For rope probes, the
end weight causes an additional preliminary positive echo (see rope probe diagram).
Launch pulse
Rod probe
Level echoes are detected as positive signals in the envelope curve. Interference
echoes can be both positive (e.g. reflections from internals) and negative (e.g. nozzles).
The envelope curve, the map and the differential curve are used for the evaluation.
Level echoes are searched for in the differential curve.
Probe end signal
Launch pulse
11 Appendix
Probe end signal
Rope probe
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