3 poly mode, 4 powr mode, 5 log mode – Micromod Micro-DCI: 53SL6000 Single Loop Controller User Manual
Page 56: 6 lim mode
6.3.3 PoLY Mode
This is a third order polynomial equation which op-
erates on an algebraic combination of the four ana-
log inputs. The constants K1 through K4 are the
coefficients for the equation. The constants K5
and K6 allow for some limited scaling of the four
analog inputs.
X
=
K4
(
AB
+
K5
)
C
+
K6
+
D
3
+
K3
(
AB
+
K5
)
C
+
K6
+
D
2
+
K2
(
AB
+
K5
)
C
+
K6
+
D
+
K1
6.3.4 PoWr Mode
This mode provides a general purpose exponential
(power) equation with the four analog inputs as-
signed in the exponent, base, multiplier, and bias.
The constants K1 through K6 provide scaling for all
four except the bias term.
X
=
K5C
+
K6
[
K1A
+
K2
]
(
K
3
B
+
K
4
)
+
D
An important use of the exponential equation is
calculating flow values using weirs and Parshall
flumes as measuring elements. The table below
gives the required assignments for three types of
weirs: rectangular, cipolletti, and triangular based
on the weirs dimensions (Length - feet, height -
inches, and x - degrees). Analog output is in gal-
lons per minute (gpm).
Power Equation Constants by Weir Type
Constant
Rectangular
Cipolletti
Triangular
Fnc.A
h
h
h
Fnc.b
0
0
0
Fnc.c
h
0
0
Fnc.d
0
0
0
K1
1
1
1
K2
0
0
0
K3
0
0
0
K4
1.5
1.5
2.47
K5
-0.6
0
0
K6
3L
3.037L
see K6
below
K6 for triangular weirs is as follows:
K6
=
2.42.9
[
tan
(
x
2
)
]
0.992
6.3.5 LoG Mode
The logarithm equation produces a base 2 logarith-
mic value of the algebraic function of the four ana-
log inputs. The constants K1 through K5 provide
scaling for the input values. Constant K5 is a mul-
tiplier which can be used to convert the base of the
logarithm. For example:
Log
10
(
x
)
=
0.301 Log
2
(
x
)
Log
e
(
x
)
=
0.6932 Log
2
(
x
)
X
=
K5 Log
2
(
A
+
K1
)
(
B
+
K2
)
C
+
K
3
K4
+
D
+
K
6
6.3.6 LiM Mode
The limiter generates both an analog and a digital
output value. The analog output reflects the scaled
A input as long as it does not exceed the scaled B
input (upper limit) or fall below the scaled C input
(lower limit). If either is exceeded, the digital out-
put will be a logical one value; otherwise, it is a
logical 0 value.
if K1A
+
K2
≥
K3B
=
K4 then
X
=
K3B
+
K4,
Y
=
1
else if K
5C
+
K6
≥
K
1A
+
K2
then X
=
K
5C
+
K6, Y
=
1
else
X
=
A Y
=
0
Micro-DCI
53SL6000 Controller
6-6