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Formula of PT filter in MFD-TAP13-PT-A

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Elka:
Hello,

I am a coffee roaster from Poland who bought a machine for roasting cofee
driven by Moeller PLC and MFD-TAP13-PT-A.
My temperature readings were heavily smoothed by PT1 filter. We switched
the filter off   but would like to know the exact formula of the filter which was damaging our data in the past.

Any help will be welcome.

radar17892:
Hi Elka,
For help, we need the PLC type (800, EC4P, ...).

PT1 filter FT in easy800 PLC:

Y(t) = [Ta/Tg] x [Kpx (x(t) - Y(t-1))]

regards Thomas

Elka:
Thank you so much! Nobody has been able to answear this question so far, even then I had asked Moeller in Germany and in Poland and send my PLC documentation to Moeller offices.

My PLC is Easy M800 and MFD Titan.
We had 2 temperatures readings, corrisponding to BT (bean temperature)  and ET (environmental temperature).


When BT was not in oscillations mode due to burner way of working (1 minute ON, 1 minute OFF) a delay in BT reading was as big as 60 s. In oscillation mode strong smoothment was observed (the amplitude of BT oscillations was cut by 2/3) . When the burner was OFF BT/ET temperatures seemed to rise and when it was OFF they seemed to decrease.

Near  local extrema the delay seemed to rise and decrease..What is K in your formula? What is Ta and Tg?
Thank you for your explanations once more..

Elka:
We have found such an item:

ftp://ftp.moeller.net/DOCUMENTATION/AWB_MANUALS/h1365g.pdf

and read on the page 33 about PT1 smoothing filter but we still don't understand what is Kpx?

we know that: (t) is probably the real temperature registered by PT100. y(t-1) is the display reading just one sample time before. Kpx is any amplification...

Ta-actual time?
Tg delay time

Elka:
we have found also an information (on Polish Elektroda.pl) tat K=0,38 for an "ideal" low pass filter..

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