Operating Principle Of Comparator 2 - Siemens SIMATIC S7-300 Manual

After you called SFC 55, switched SM 335 to the special operating mode "Comparator" and
enabled only Comparator 1, SM 335 compares the analog value at the specified input with
the reference value.
The module continues to update the analog inputs which can be read by means of PEW.
SM 335 terminates the special operating mode "Comparator" after the specified analog value
has been reached.
After having terminated the special operating mode "Comparator", SM 335 outputs the
analog values specified in SFC 55. SM 335 outputs these analog values until you write a
new analog value to the SM 335. The new analog value must differ at least by one bit from
the analog value which was output prior to activation of the special operating mode
"Comparator".
Note
Comparator 1 does not operate at the cycle time time of 1 ms.
Comparator 2
The following figure shows how Comparator 2 works:
Figure 5-4

Operating principle of Comparator 2

SM 335 - High-speed analog mixed module for SIMATIC S7-300
Manual, 02/2009, A5E02409063-01
Special operating modes of SM 335
5.2 Special operating mode "Comparator"
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