S7-200 Specifications
A-42
S7-200 Programmable Controller System Manual
A5E00066097-02
Input Calibration
The calibration adjustments affect the instrumentation amplifier stage that follows
the analog multiplexer (see Figure A-22). Therefore, calibration affects all user
input channels. Variations in the component values of each input circuit preceeding
the analog multiplexer will cause slight differences in the readings between
channels connected to the same input signal even after calibration.
To meet the specifications contained in this data sheet, you should enable analog
input filters for all inputs of the module. Select 64 or more samples in calculating
the average value.
To calibrate the input, use the following steps.
1. Turn off the power to the module. Select the desired input range.
2. Turn on the power to the CPU and module. Allow the module to stabilize for 15
minutes.
3. Using a transmitter, a voltage source, or a current source, apply a zero value
signal to one of the input terminals.
4. Read the value reported to the CPU by the appropriate input channel.
5. Adjust the OFFSET potentiometer until the reading is zero, or the desired
digital data value.
6. Connect a full-scale value signal to one of the input terminals. Read the value
reported to the CPU.
7. Adjust the GAIN potentiometer until the reading is 32000, or the desired digital
data value.
8. Repeat OFFSET and GAIN calibration as required.
Calibration and Configuration Location for EM 231 and EM 235
The calibration potentiometer and configuration DIP switches are located on the
right of the bottom terminal block of the module, as shown in Figure A-20.
EM 231
EM 235
OffsetGain
Fixed Terminal Block
123456
DIP ON ↑
Gain
Fixed Terminal Block
123456
DIP ON ↑
↑On
↓Off
Configuration
Configuration
↑On
↓Off
Figure A-20 Calibration Potentiometer and Configuration DIP Switches for EM 231, EM 235
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