Configuration of the SIMATIC Manager
6.2 Hardware configuration
SM331; AI 8x12 Bit Getting Started part 1: 4 -20mA
6-12
Getting Started, 11/2006, A5E00253410-02
Explanation of the individual settings
Measuring type:
2DMU and 4DMU stand for 2-wire and 4-wire current transducers
--- means that the channels are deactivated. If you deactivate channels, the remaining
channels are processed faster.
Measuring range modules
The required setting of the measuring range module is displayed.
Interference frequency (Interference frequency suppression)
The frequency of your AC power system can interfere with the measured value, particularly
when measuring in low voltage ranges and using thermocouple elements. With this
parameter you specify the frequency of your power supply on site.
This parameter also influences the granularity, integration time and the basic execution
period of the channel group.
●
Resolution (accuracy)
The analog value is stored in a 16-bit word.
●
Integration time
The module requires a certain amount of time to measure the analog signal. This time is
called integration time. The higher the required accuracy is, the longer the module needs
for measuring the voltage.
●
Basic processing time
Besides the integration time, the module also needs a certain amount of time to provide
the binary value.
Relationship between accuracy, interference frequency and integration period
Resolution
Interference
frequency
Integration time
Basic processing time
9 bits
400 Hz
2.5 ms
24 ms
12 bits
60 Hz
16.6 ms
136 ms
12 bits
20 Hz
20 ms
176 ms
14 bits
10 Hz
100 ms
816 ms
Hardware interrupt:
Only the channels 0 and 2 have hardware interrupt capabilities. You can use hardware
interrupts to trigger an alarm when the analog signal exceeds its high or low limit.
Finish the hardware configuration:
Close the window with the configuration.
Compile and save the project with the command Station > Save and Compile (Ctrl+S)
This completes your hardware configuration for the project.
