Initialization And Back Calculation Requirements; Split Range And Sequence Operation - Emerson Fisher Fieldvue DVC6030f Instruction Manual

Y
100%
(X
11
0%
(X
12
0%
OUT 1
0%
100%
50%
SP
Figure 5-21. OUT with LOCKVAL True
Refer to figure 5-21 for an example of LOCKVAL =
true, and figure 5-22 for an example of LOCKVAL =
false. The parameter LOCKVAL provides an option to
specify whether OUT_1 remains at its ending level
when control is switched to OUT_2, or goes to Y
LOCKVAL is true, OUT_1 remains at its ending value
when X is greater than X
12
OUT_1 goes to Y when X is greater than X
11
Some hysteresis in the switching point may be
required because the output may change by a full
stroke of the valve. HYSTVAL [12] contains the
amount of hysteresis. If X < = X12−HYSTVAL,
OUT_1 may be determined by the calculated y value.
If X12−HYSTVAL < X < X12 and X has not reached
X12 since it was less than X12−HYSTVAL, OUT_1
may be determined by the calculated y value. If
X12−HYSTVAL < X < X12 and X has reached X12
since it was less than X12−HYSTVAL, OUT_1 may be
determined by the LOCKVAL setting. If X12 < X,
OUT_1 may be determined by the LOCKVAL setting.
March 2006
Split Range
(X22 , Y22)
, Y )
11
OUT_1
OUT_2
(X , Y )
, Y )
21 21
12
50% 100%
SP
Figure 5-20. Split Range and Sequence Operation
OUT 1 remains at
end point when OUT_2
is non-zero
OUT 2
. If
11
. If LOCKVAL is false, then
.
12
OS Function Block
Sequencing
Y
(X
100%
OUT_1
0%
(X , Y )
11 11
X
0% 50%
SP
OUT 1
0% 50%
SP
Figure 5-22. OUT with LOCKVAL False
Initialization and Back Calculation
Requirements
Refer to figure 5-23, Output Splitter Configuration,
where:
PID1 = Upstream driving controller or function block.
Splitter = Split range function block being described.
AO = Receiver of OUT_1 for 0−50% range of SP
PID2 = Receiver of OUT_2 for 50−100% range of SP
CAS_IN of the Splitter receives the OUT of PID1.
BKCAL_IN of PID1 receives BKCAL_OUT of the
Splitter. CAS_IN of the AO receives OUT_1 of the
Splitter and PID2 receives OUT_2 of the Splitter.
BKCAL_IN_1 of the Splitter receives BKCAL_OUT of
the AO and BKCAL_IN_2 of the Splitter receives
BKCAL_OUT of PID2.
, Y ) (X , Y )
12 12 22 22
OUT_2
(X , Y )
21 21
X
100%
OUT 2
OUT_1 goes to zero
OUT_2 becomes
100%
5-117
5