LOGO-0BA7 function_analog_filter

Hello all,

the LOGO-0BA7 brings along different new function blocks.

In this contribution i wants to contribute an application-oriented evaluation of the block "Analog filter" :

The block "analog filter" makes a calculationcalculation of a so-called gliding average from n values at the past time. This is circuitcircuit-technical only with very high expenditure possible, so that of me only circuits were publishedfor n = 4 , 8 and/or 10. In this respect the achievementachievement of this block is remarkable, because according to HB n can be in at the most 256. The determinationdetermination from n, however, comparably few predefined values bound (pitiful, a free definition of 1 to 256 and for this purpose still by reference would be very useful, particularly then, if also another external triggering was possible for this purpose).

CriticallyCritically I evaluate the predefined determinationdetermination of the chronologicalchronological distance of the value gatheringgathering, because this is (exclusively) coupled to the (variable) LOGO!-cycle frequency (= program frequency) (from HB: „LOGO! get an analog value in every program cycle. The number of the program cycles is thus like the parameterizedparameterized number of scannings.“). The cycle frequency is, however, variable and therefore final to the term of the circuitcircuit from viewview of a programmer/customer of a filter only for the filtering of analog values suitable, that come from an analogous block output (in the cycle timetime) and not immediate or indirect of an analog input! The chronologicalchronological distances of the gatheringgathering of the values for the filtering of the analog inputs should unconditionalunconditional onto the sampling frequency and/or at the LOGO! to be adjustable onto the updateupdate frequencies of the analog inputs (therefore all 50 ms and/or 300 ms occur; where appropriate also of multiples of that, at what then however is, a to low scanning frequency the consequence). I think, because that, the calculation resalts can be wrong (it is a function of the real curve datas).

--> UPSHOT: The block "analog filter" is not unfortunately suitable a correct filtering unit of the analog inputs reach, because unfortunately this block "analog filter" works on basis of the changeablechangeable LOGO!-cycle frequency that deviates from the sampling rates of the analog inputs (300 ms withwith basic modules and 50 ms near extra modules AM2) clearly. The results can differ where appropriate clearly from the real signal values! Because on the other hand an external triggering of the sampling times is not possible, this block can not use in possibilities (in most cases) either to the general calculationcalculation of gliding averages.

Best regards
Betel