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SIEMENS
Objectives
- Know Analog Value Processing.
- Set The Measuring Range Module.
- Assign Parameters To Analog Modules
- Use Standard Function For Scaling
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Process
Physical
quantity
Standard
analog signal
Sensor Transducer
• Pressure
• Temperature
• Flow
• Speed
• Viscosity
± 500mV
± 1V
± 5V
± 10V
± 20mA
4 to 20mA
DAC
PQW ...
PQW ...
:::
PQW ...
Analog output module
ADC
PIW ...
PIW ...
:::
PIW ...
Analog input module CPU
:
:
:
:
:
:
L PIW 340
T PQW 360
:
Analog
actuator
Physical
quantity
......................................
Analog Input & Output Modules
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Measuring Range Module
The measuring range modules with their coding
keys are located on the left-hand side of the
module. You must set them correctly before
installing the module.
The possible settings are "A", "B", "C" and "D".
The settings for the various types of
measurement and measuring ranges are printed
on the module.
On some modules, several channels are grouped
together to form a channel group. In this case,
the coding key setting applies to the whole
channel group.
Analog Module Parameters
Parameter Assignment
The tool for assigning parameters to analog
modules is HW Config. After downloading from
the programming device to the S7-300, the
parameters are stored in the CPU. The CPU
transfers these parameters to the relevant analog
modules.
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Analog Input Module
Measuring Type
Click the field to display and select the available
measurement types.
Measuring Range
Click the field to display and select the available
effective ranges for the corresponding
measurement type.
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Analog Output Module
Output Range
Click the field to display and select the available
output ranges for the selected output type.
Reaction to CPU
Select how the outputs are to react in the case of
a CPU STOP
• Switch to Substitute Value (SSV)
-The substitute value is set to ”0” by default;
that is, all outputs are switched off. You can set
the substitute values for each individual output
in the ”Substitute value” line. The substitute
values must lie within the rated range.
• Retain Last Value (RLV)
-If the module is to retain the last value output
before the CPU enters the STOP mode.
• Outputs Without Voltage or Current (OWVC)
-If the module is to switch off the outputs on
CPU STOP (V/I = 0 V/mA).
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Range
Overflow
Overrange
Rated range
Underrange
Underflow
Meas.range
± 10V
Voltage
such as:
>= 11.759
11.7589
:
10.0004
10.00
7.50
:
-7.5
-10.00
- 10.0004
:
- 11.759
<= - 11.76
Units
32767
32511
:
27649
27648
20736
:
-20736
-27648
- 27649
:
- 32512
- 32768
Meas.range
4 to 20mA
Current
such as:
>= 22.815
22.810
:
20.0005
20.000
16.000
:
:
4.000
3.9995
:
1.1852
<= 1.1845
Units
32767
32511
:
27649
27648
20736
:
:
0
- 1
:
- 4864
- 32768
Meas.range
-200...+850ºC
Temperature
such as Pt100
Units
32767
10000
:
8501
8500
:
:
:
-2000
- 2001
:
- 2430
- 32768
>= 1000.1
1000.0
:
850.1
850.0
:
:
:
-200.0
- 200.1
:
- 243.0
<= - 243.1
Meas.range
0...300Ohm
Resistance
such as:
>=352.778
352.767
:
300.011
300.000
225.000
:
:
0.000
Negative
values
not
possible
Units
32767
32511
:
27649
27648
20736
:
:
0
- 32768
- 1
:
- 4864
Analog Value Representation of Different Measuring Ranges
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HI_LIM = 500.0
LO_LIM = 0.0
Bipolar (M 0.0 = 1)
HI_LIM = 500.0
LO_LIM = 0.0
Unipolar (M 0.0 = 0)
OUT
IN
OUT
Scaling Analog Input Values
Scaling
The analog module encrypts the voltage
range of -10V to +10V in the value range of
-27648 to +27648. The conversion of this
value range to the original physical size
(such as 0 to 500 l) is called scaling.
The standard block FC 105 is used for
scaling the analog value. FC 105 is
supplied with the STEP 7 software in the
"Standard Library" in the "TI-S7
Converting Blocks" S7 program.
0 27648-27648276480
IN IN
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Editor's Notes
Sensor
Measuring sensors respond to changes in the quantity to be measured.
Transducer
Measuring transducers convert these above-mentioned changes into standard analog signals.
Analog Output
The &quot;T PQW...&quot; transfer instruction is used to write the analog values the user program calculated to an analog output module.
Analog Actuators
The analog output signals are standard signals such as ± 10V or 4 to 20mA.
IN
The analog value at input IN can be read in from the module directly or can be passed from a data interface in INT format.
LO_LIM, HI_LIM
Inputs LO_LIM (low limit) and HI_LIM (high limit) are used for specifying the limits of the basic physical size. In the example, a conversion to the range 0 to 500 liters is made.
OUT
The scaled value (physical size) is stored as a real number at output OUT (LO_LIM &lt;= OUT &lt;= HI_LIM).
BIPOLAR
At input BIPOLAR you can specify as to whether only positive or also negative values are to be converted. If an operand with the state ´0´ (unipolar) is passed to the parameter, scaling is made for the range 0 to +27648. If the operand state is ´1´ (bipolar), scaling is made for the range -27648 to +27648.
RET_VAL
The output RET_VAL supplies the value 0 when execution is error free.
