34
Output current (4 to 20 mA) =
16 mA + 4 mA
[%]
Entry for “50 % point”:
e.g.:
10 % of measured value
End
0
Output current
Y
X
Process variable
• Function characteristic
Nonlinear output current characteristic: allows measurements over several
decades, e.g. measuring very low values with a high resolution and high
values with a low resolution.
Required: Entering a value for 50 % output current.
100
50
Equation
(1+K)x
1+Kx
E + S - 2 * X50%
X50% - S
K =
M - S
E - S
x =
S:
Start value at 4 mA
X50%:
50% value at 12 mA (output current range 4 to 20 mA)
E:
End value at 20 mA
M:
Measured value
Logarithmic output curve over one decade:
S:
10 % of maximum value
X50%:
31.6 % of maximum value
E:
Maximum value
Logarithmic output curve over two decades:
S:
1 % of maximum value
X50%:
10 % of maximum value
E:
Maximum value
