5.7
Conversion, cycle, settling and response time of analog modules
Conversion time of analog input channels
The conversion time is the total of the basic conversion time plus additional processing times
of the module for:
● Resistance measurement
● Wire break monitoring
The basic conversion time depends directly on the conversion method of the analog input
channel (integrating method, actual value conversion.)
The integration time of integrating conversions has a direct influence on conversion times. The
integration time depends on the interference frequency suppression you set in STEP 7.
For information on basic conversion times and additional processing times of the various
analog modules, refer to the specifications of the relevant module.
Cycle time of analog input channels
The analog/digital conversion and the transfer of the digitized measured values to memory or
to the backplane bus take place sequentially. In other words, the analog input channels are
converted one after the other. The scan time - in other words, the time elapsing until an analog
input value is again converted - is the sum of the conversion times of all activated analog input
channels of the analog input module.
The figure below provides an overview of the cycle time elements for an n-channel analog
module.
Conversion time, channel 1
Conversion time, channel 2
Conversion time, channel 3
Cycle time
Figure 5-2
Scan time of an analog input or output module
Basic execution time of the analog input channels
The basic execution time corresponds to the cycle time for all the enabled channels.
Setting of the smoothing of analog values
You can set the smoothing of the analog values in STEP 7 for some analog input modules.
Analog modules
5.7 Conversion, cycle, settling and response time of analog modules
S7-400 Automation System Module Data
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Reference Manual, Ausgabe 11/2016, A5E00850736-08