Analog modules
6.4 Analog input module SM 331; AI 8 x 16 Bit; (6ES7331-7NF10-0AB0)
S7-300 Automation System Module data
Manual, 08/2006, A5E00105505-04
6-25
Cycle time of module in 8-channel mode
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. When you set an interference frequency "All", the channel conversion
time amounts to 88 ms. The module then has to toggle to the channel of the group via Opto-
MOS relay. Opto-MOS relays require switching and settling times of 7 ms. The table below
shows this relationship.
Table 6-12 Cycle times in 8-channel mode
Interference frequency (Hz) Channel cycle time (ms) Module cycle time
(all channels)
50 83 166
60 72 144
400 23 46
50/60/400 95 190
4-channel mode operating mode
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 6-6 4-channel mode cycle time
Module cycle time
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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