Function blocks
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www.EatonElectrical.com
MN05013005E
219
X
i
(
t
) = Actual value with scan time
t
X
i
(
t
–1) = Actual value with scan time
t
– 1
Scan time T
c
Scan time T
c
determines the duration of the interval in which
the function block is called by the operating system for
processing. The value range is between 0 and 6553.5 s.
If the value 0 is set, the cycle time of the device is the pause
time between the function block calls.
Manual mode of the PID controller
A value must be present at the
>MV
input in order to set the
manipulated variable directly. If the coil DC..SE is activated,
the value at
>MV
is transferred as manipulated variable
QV>
.
This value is present for as long as the DC..SE coil is activated
or the value at the
>MV
input is changed. If coil DC..SE is
deactivated, the control algorithm is reactivated.
Signal smoothing filter
EZD provides 32 signal smoothing filters FT01 to FT32. The
function block allows you to smooth noisy input signals.
J
The device cycle time varies according to the length of the
program. With a scan time of 0 s, this may cause an
irregular control response.
J
Use the Set cycle time function block (
order to keep the cycle time of the device constant.
J
Extreme changes in the manipulated variable can occur
when the manual manipulated variable is transferred or
deactivated.
J
If the function block is running in UNI (unipolar) mode, a
negative signed manipulated variable value will be output.
