Configuration
3.13
Figure 3.11 - Simatic PDM - Online Configuration - Set/Preset for Totalizer Block
Current Trim
The
IF303
provides the capability of making a trim in the input channels, if necessary.
A trim is necessary if the indicator reading of the transducer block output differs from the actual
physical output. The reason may be:
•
The user's current meter differs from the factory standard.
•
The converter had its original characterization shifted by over-load or by long term drift.
The user can check the calibration of the transducer output by measuring the actual current in the
input and compare it with the device’s indication (of course an appropriate meter shall be used). If a
mismatch is detected, a trim can be done.
Trim can be done in two points:
Lower Trim
: Is used to trim the lower value of the input range.
Upper Trim
: Is used to trim the upper value of the input value.
These two points define the linear characteristic of the output. Trim in one point is independent from
the other.
There are at least two ways of doing the trim: using local adjustment or using
a Configuration Tool
(see below examples using
Simatic PDM
from
Siemens
).
When doing the trim, make sure you are using an appropriate meter (with the necessary accuracy).
Via Simatic PDM
The channel number of the AI block is related to the transducer’s terminal block number. Channel
number 1,2,3 corresponds bi-univocally to the terminal block with the same number. Therefore, all
the user has to do is to select combinations: (1, 1), (2, 2), (3, 3), for (CHANNEL, TERMINAL
NUMBER).
It is possible to calibrate the current inputs of the transmitter by means of parameters
CAL_POINT_LO and CAL_POINT_HI.
Let’s take the lower value as an example:
Supply 4 mA or the lower value to the terminal block and wait until the readout of parameter
PRIMARY_VALUE stabilizes.
Write 4.00 or the lower value in parameter CAL_POINT_LO. For each value written a calibration is
performed at the desired point.
The user can
select: Totalize,
Reset and Preset
and enter the value
for preset
operation.
The user can
monitor the
totalizer output.