User's Manual
Table Of Contents
- 8 Parameter reference
- 9 Service and maintenance
- 10 Diagnosing and troubleshooting
- 11 Technical data
- 12 Dimension drawings
- 12.1 Threaded horn antenna
- 12.2 Threaded horn antenna with extension
- 12.3 Flanged horn antenna
- 12.4 Flanged horn antenna with extension
- 12.5 Flanged encapsulated antenna (2"/DN50/50A sizes only)
- 12.6 Flanged encapsulated antenna (3"/DN80/80A sizes and larger)
- 12.7 Threaded PVDF antenna
- 12.8 Threaded connection markings
- 12.9 Raised-Face flange per EN 1092-1 for flanged horn antenna
- 12.10 Raised-Face flange per EN 1092-1 for flanged encapsulated antenna
- 12.11 Flat-Face flange
- 12.12 Process connection tag (pressure rated versions)
- A Appendix A: Technical reference
- B Appendix B: PROFIBUS PA profile structure
- C Appendix C: Communications via PROFIBUS
- D Appendix D: Certificates and Support
- 13 List of abbreviations
- 14 LCD menu structure
- Glossary
- Index
Appendix B: PROFIBUS PA profile structure
B.2 Block Model
SITRANS LR250 (PROFIBUS PA)
Operating Instructions, 01/2014, A5E32221386-AB
227
How an Analog Input Function Block works
The AIFB provides a linear conversion to any desired units.
1. The AIFB Input value is the processed output value of the Transducer Block, in Transducer
Block units.
2. The user selects the desired AIFB output units and scaling is applied.
3. Damping may be applied based on a time constant provided by the user. See Damping
(Page 210) for details.
4. The status of the input value from the Transducer Block is checked. If the status is Bad, a
Fail-safe condition occurs. The output is determined by the setting for Failsafe Mode.
5.
Actual Mode (2.6.2.)
allows the entire AI block to be overridden by a Manual Output value.
See
Actual Mode (2.6.2.)
for details.
6. The value is checked against the user-defined warning and alarm limits. The upper and lower
limits are defined in units corresponding to the Output range, and a limit hysteresis can be
used to adjust the sensitivity. See
Alarms and Warnings (2.6.7.)
for details.
7. The output value (OUT) is communicated via cyclic data transfer.