YOKOGAWA UP35A, User Manual

Page: 116 / 412

7-5
IM 05P02D41-01EN
Input (PV) Functions
7
7.1.4 Correcting Input Value
(1) Setting Bias and Filter
Description
PV Input Bias
The PV input bias allows bias to be summed with input to develop a measured value for
display and control use inside the controller.
This function can also be used for fine adjustment to compensate for small inter-
instrument differences in measurement reading that can occur even if all are within the
specified instrument accuracies.
PV input bias is used for normal operation.
PV input value + = PV input bias PV value inside the controller
Temperature sensed
by thermocouple
Compensation
value
Estimated material
temperature
PV Input Filter
If input noise or variations cause the low-order display digits to fluctuate so that the
displayed value is difficult to read, a digital filter can be inserted to smooth operation.
This filter provides a first-order lag calculation, which can remove more noise the larger
the time constant becomes. However, an excessively large time constant will distort the
waveform.
PV input filter is used for normal operation.
Actual input With a small time constant With a large time constant
Input
Filtering for 2 sec
Filtering for 10 sec
Analog Input Bias
Analog input bias is used to correct sensor-input characteristics, compensating lead wire
errors, and so on.
Analog Input Filter
The analog input filter is used to remove noise from an input signal. This filter provides
a first-order lag calculation, which can remove more noise the larger the time constant
becomes. However, an excessively large time constant will distort the waveform.
7.1 Setting Functions of PV Input