J; Profi;e structure PA
Description of the blocks
Level Transducer Block function groups
Note: Primary Value (PV) is the default measured value; Secondary Value 1 (SV1) is an equivalent value.
The figure below shows the signal flow of measured values from the sensor through the Level Transducer Block into the output value (Primary Value/ Level; Secondary Value 1 / Level; or Secondary Value 2 /Distance. The LTB implements all of the basic parameters
(see parameter diagram on page 101).1
Level Transducer Block
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| Primary Value |
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| Sensor Value | Level | Level |
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| (sensor units) | (level units) | (level units) |
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Sensor | Sensor | Level |
| Linearization | PV |
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technology | calibration |
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| (turned off)1 |
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| Level |
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| AIFB1 |
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| Offset | Linearization |
| (Analog |
| Sensor | High | Low | Type | SV1 | Input) |
| Offset | Calibration | Calibration | Secondary Value 1 |
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| Point | Point |
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| High Level | Low Level | [Level] |
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| Point | Point | (Level Units) |
| AIFB2 |
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| Calibration |
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| SV2 | (Analog | ||
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| Type |
| Input) | ||
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| Secondary Value 2 |
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| [Distance] |
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| (Sensor Units) |
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How the Level Transducer Block works:
1.The sensor technology block selects the proper echo. See Echo selection on page 72 for more detail.
The sensor value (in sensor units) is checked to see if it is within its measuring limits. If the limit is exceeded, this results in a Bad status and the error message Failure in measurement. The sensor value is stored in Sensor Value.
The analog signal from the sensor is transformed into a digital signal.
A Sensor Offset (default 0) provides compensation if necessary for differences between the vessel reference point and the sensor reference point.
1.A Linearization module is required by the PROFIBUS PA specifications. The Linearization block is turned off in SITRANS LR 460.
Page | SITRANS LR 460 (PROFIBUS PA) – INSTRUCTION MANUAL | 7ML19985JM01 |
