Minimum Value Selection Mi1 To Mi3; Correction Computer For Ideal Gases Re1 - Siemens SIPART DR22 Manual

1 Technical Description
1.5 Functional description of the structure switches
1.5.2 Analog input signal processing freely connected (S4 = 1)
If only 2 inputs are required, the 3rd input must be set outside the working range of the two
inputs to a minimum value otherwise minimum value limiting takes place.

1.5.2.4 Minimum value selection Mi1 to Mi3

Mi1.F to Mi3.F
Mi .F
E1
ncon Mi .1
E2
Min.
ncon Mi .2
E3
1.050
Mi .3
Figure 1-10 Function block minimum value selection
With the preset the smaller value of E1 or E2 is connected through to A and at the same time
limited to the value of E3 (105%). Typical applications are minimum value selection circuits. If
only 2 inputs are required, the 3rd input must be set outside the working range to a maximum
value, otherwise a maximum value limiting takes place.

1.5.2.5 Correction computer for ideal gases rE1

rE1
rE1 .F
rE1 .1
1.000

ΔP
E2
rE1 .2
ncon
E
ncon
rE1 .3
3
tA, tE, PA, PE
Figure 1-11 Function block correction computer rE1 for ideal gases
The rooted signal of the active pressure must be applied at input c**.1. The measuring ranges
are normalized to the calculation state with the parameters PA, PE, tA, tE (correction quotients
start/end for pressure and temperature).
Range of Application
The correction computer is used to calculate the flow of gases from the active pressure Δp
depending on pressure and temperature. The medium must be in pure phase, i.e. so that no
liquid separations may take place. This should be noted particularly for gases close to the
saturation point.
Errors due to fluctuating status variables of the medium (pressure, temperature) are corrected
by the flow correction computer here.
28
nr
A = min (E1, E2, E3)
The smallest of the three input values is
A
Mi ..4
connected through to the output.
nr
x
A
rE .4

f(E2·E3)
(oFPA)


A = · f (E2, E3)
Δp
(PE – PA) E2 + PA
f (E2, E3) =
(tE – tA) E3 + tA
Manual
SIPART DR22 6DR2210
C79000-G7476-C154-03