Siemens SIMATIC ET 200AL, System Manual

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Supported functions
7.1 Calibrating analog modules
Analog value processing
Function Manual, 06/2014, A5E03461439-AC
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The required calibration values of the selected channel according to the measuring range
configured for this channel are specified once again during the user calibration.
Note
The calibration can take place in RUN mode as well as STOP mode of the CPU. If the CPU
is in RUN, the calibration value that was last collected prior to the start of the calibration is
supplied for the duration of the calibration.
The module channel to be calibrated cannot process any new process values during the
user calibration. All analog input values of the module are set to 0x7FFF ("Invalid analog
value") until the end of the calibration. When the value status is enabled, the value status of
the signal is set to "invalid" for the duration of the calibration.
You must provide a voltage and/or temperature during a user calibration. To do so, use the
corresponding external wiring and an external voltage/temperature transducer. The field
"Command" includes numbers of pins to which you can connect the calibration stimulus.
The first pin number identifies the positive connector, the second pin number the negative
connector. The accuracy of the calibration depends on the accuracy of the provided
voltage/temperature.
Note
To ensure that the module retains the specified measuring accuracy after the user
calibration, the provided voltage/temperature must be twice as accurate as specified for the
module. Inaccurate voltages or temperature result in a faulty calibration.
The figure below shows an example of channel calibration with "Voltage" measurement,
measuring range "+/- 10 V".
Figure 7-2 Manual calibration