Analog modules
6.10 Analog input module SM 331; AI 8 x TC; (6ES7331-7PF11-0AB0)
S7-300 Automation System Module data
6-98 Manual, 08/2006, A5E00105505-04
Cycle time of module in 8-channel mode (software filter)
However, the channel conversion time is oriented on the programmed noise suppression. At
a set interference frequency of 50 Hz, the channel conversion time is 76 ms, including
communication time. At a set an interference frequency of 60 Hz, the channel conversion
time is 65 ms. You can reduce channel conversion times to 16 ms by setting an interference
frequency of 400 Hz. As in "hardware filter, 8channel" mode, the module has to toggle to the
second channel of the group within a changeover time of 7 ms using the Opto-MOS relays.
The table below shows this relationship.
Table 6-30 Cycle times in 8-channel mode (software filter)
Programmed noise suppression Channel cycle time* Module cycle time (all channels)
50 Hz 83 ms 166 ms
60 Hz 72 ms 144 ms
400 Hz 23 ms 46 ms
* Channel cycle time = channel conversion time +7 ms channel changeover time within the group
4-channel mode (hardware filter)
In this mode, the module does not toggle between the channels of the various groups. The
four ADCs of the module simultaneously convert channels 0, 2, 4 and 6.
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Figure 6-31 4-channel mode cycle time (hardware filter)
Cycle time of module in 4-channel mode (hardware filter)
In 4-channel mode, the converted value tunes to 100 % within 80 ms and is updated every
10 ms. The channel and module cycle time are always identical, because the module does
toggle between the channels of a group: 10 ms.
Channel conversion time = channel cycle time = module cycle time = 10 ms
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