Analog Input Function Blocks 1 And 2 - Siemens Sitrans PROBE LU Instruction Manual

3. Then linearization can be carried out to accommodate complex tank shapes, or to
provide level to volume conversion.
4. The LTB provides four possible outputs
• Primary Value (PV) / Level or Volume
• Secondary Value 1 (SV1) / Level
• Secondary Value 2 (SV2) / Distance 1 (sensor units)
• Secondary Value 3 (SV3) / Distance 2 (any level units, except %)
Electronics temperature
The transducer block also monitors the internal temperature of the device electronics. If
the temperature exceeds permitted limits, it does not change the sensor value, but it does
change the status.The permitted limits correspond to the permitted ambient temperature
limits.
If a temperature limit is exceeded, the status changes. Peak indicators
check the maximum and minimum temperatures that have occurred.

Analog Input Function Blocks 1 and 2

The figure below shows how measured values are processed within the two Analog
Input Function Blocks to produce the device outputs, which are communicated via cyclic
transfer to PROFIBUS PA, and displayed on the LCD.
Analog Input Function Block function groups (simulation, mode, and status)
Operator
Simulate
Parameter
enable
simulate
value and
2
Process Variable
status
from LTB
(Function Block
input)
Value Status
1.
Open View menu, scroll down to Peak Values, and click on Temperature tab in the
Peak Values window.
2.
The output from the Level Transducer Block can be called the Primary Value (PV) or
Secondary Value (SV1, SV2, or SV3). When it becomes the input to the AIFB, it is called
the Process Variable.
Page 58 SITRANS Probe LU (PROFIBUS PA) – INSTRUCTION MANUAL
on
FB
Value
algorithm
Status
off
Operator
MAN
OUT
Out of
OUT
Service
AUTO
Failsafe
MODE and
STATUS
handling
1
allow you to
2
Alarm
OUT
Limit
Value Status
Check
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