Analog Output Block - Siemens SITRANS P300 Operating Instructions Manual

DV Measurement BAD
type
9
Users DV0 = BAD
Characteristic
curve is faulty
If falling characteristic curves are being used in the blocks, the meanings of HIGH LIMIT and
LOW LIMIT are swapped around.
If you mix falling and rising characteristic curves, the meanings will be swapped each time a
falling characteristic curve is run.
7.4.9

Analog output block

Introduction
The analog output block converts the value provided by the dynamic Primary Variable (PV)
into a current value of 4 to 20 mA. When you actuate the measurement type selector, you
automatically define the zero point and limit point to the current values 4 and 20 mA,
respectively. By default, the limit values of the corresponding device variables, as entered by
you when setting your measurement type, will be used for scaling the analog output.
Example for measurement type "Level"
This means that for a "Level" device variable as PV, 10 m corresponds to the value for 4 mA
and 20 m corresponds to the value for 20 mA. You can change this setting again in the
analog output block. This is done by restricting the range of the "Level" device variable for
scaling the output current to e.g. 12 to 18 m. This downscaling has no effect on the previous
block scaling. In this case, a current of 4 mA is output for a measured height of 12 m, and a
current of 20 mA for 18 m.
SITRANS P300 with HART communication
Operating Instructions, 06/2005, A5E00359579-02
MANUAL UNCERTAIN
When DV0 DV0=
is simulated UNCERTAIN
Input value is
outside the
specified
characteristic
curve range
Operating functions via HART
7.4 Selecting the measurement type
CONSTANT HIGH LIMIT
Characteristic DV0 = HIGH
curve is faulty LIMIT
DV not active Characteristi
c curve for
maximum
value with
gradient 0
LOW LIMIT
DV0 = LOW
LIMIT
Characteristic
curve for
minimum value
with gradient 0
7-13