SITRANS LR250 (PROFIBUS PA)
Operating Instructions, 08/2014, A5E32221386-AC
257
Appendix B: PROFIBUS PA profile structure
PROFIBUS Level Device Design
The device follows the profile block model and is implemented as a Profile 3.0, Class B, PA
device. Standard profile parameters are used to program the level transducer block.
The Block Model represents how measured values are recorded and processed. All data is
viewed from the perspective of the DCS or PLC, so information from the sensor is an input.
The functions of the device are divided into blocks with different areas of responsibility. The
blocks are configured by parameters.
The device is implemented with one Physical Block, one Transducer Block (TB), and two Analog
Input Function Blocks (AIFB1 and AIFB2).
The Physical Block handles functionality and descriptions relating to the device as a whole: for
example, LCD Contrast (functionality) and Firmware Revision and Tag (descriptions).
The Transducer Block carries out adjustments to the sensor, such as level calibration and
volume calibration. It supplies the measurement value [Primary Value (PV), Secondary Value 1
(SV1), or Secondary Value 2 (SV2)] utilized by either or both of the AIFBs.
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