WIKA DI35 - Manual (Page 30)

6 Commissoning, operation
30 WIKA operating instructions digital indicator DI35-M
Temperature measurement PN0 = 13…29
For the temperature measurement, the scaling cannot be changed by the
user and is only determined from the standardized sensor range. Sensor-
caused variations can be balanced by offset shift (PN5) on the characteristic
line.
Sensor calibration for
resistance / current / voltage PN0 ≥ 30
With the sensor calibration, the unit can be calibrated or set up directly via the
sensor signal or via a calibrator. For this, the measuring signal must be
connected to the input of the unit. The respective display value (SCALE) must
then be saved under the program number PN1 (full scale) and PN2 (offset).
The sensor signal is measured via the factory parameter and displayed as
current or voltage. A measurement must be started by shortly pushing the [P]
key. Through this process with two calibration points, the unit is matched up
with the measuring section. For more far-reaching adjustments to the
characteristic line of the sensor, a linearization can be activated.
At the resistance measurement, only the display value (SCALE) is
parameterised. The adjoining sensor signal (INPUT) will not be displayed, but
directly absorbed unit-intern. For linearization of the parameter at least PN1
(final value) or PN2 (zero point) must be preset.
Linearization PN100
The DI35-M offers the possibility to linearize, with up to 30 additional
setpoints, non-linear sensors for the display of the measuring values and their
subsequent processing (analog output).
The number of the desired setpoints is determined under PN100. Be aware of
choosing the one that makes the most sense, as it can lead to a malfunction
of the device in case of no adjustment.
Approach to sensor calibration PN0
≥ 33
To program e.g. 5 additional calibration points, 5 must be entered under
PN100.
Subsequently, for each of the calibration points, the voltage/current must be
applied to the unit and the respective display value programmed under the
following program numbers PN101 – PN105.
The sensor signal must be consistently parameterized. A gap of at least +1
digit to the previous display value must be adhered to, otherwise the input will
be refused and no confirmation of the saving will be given.
Example:
Linearization of a pressure transducer for 0...100 mbar with an
output of 0...20 mA. The display value before correction can be
either calculated from the known characteristic line of the
transducer or be determined empirically.