Yokogawa YVP110 - Manual (Page 103)

<18. AR Function Block>
18-4
IM 21B04C01-01E
8) Polynomial computation
func = PV + t_1 2 + t_2 3 + t_3 4
9) HTG-level compensation
func = (PV - t_1) / (PV - t_2)
10) Polynomial computation
func = PV + t_1 × PV 2 + t_2 × PV 3 + t_3 ×
PV 4
* Precaution for computation
Division by “0”: If a value is divided by “0,” the
calculation result is interpreted as
10 37 and, depending with core, a
plus sign is added to it.
Negative square root: The square root of an
absolute value is extracted
and a minus sign is added
to it.
18.3.2 Compensated Values
In computing equations 1) to 5) in 18.3.1, the value
“f” is restricted by the COMP_HI_LIM or COMP_
LO_LIM parameter. In this case, the value “f” is
treated as follows:
If “f” > COMP_HI_LIM,
f = COMP_HI_LIM
If “f” < COMP_LO_LIM,
f = COMP_LO_LIM
18.3.3 Average Calculation
In computing equation 6) in 18.3.1, the average
of input value is calculated. Here, it is necessary
to obtain the number of inputs, N. For this,
determination is made to see if the sub-status of
each input is “Not Connected.” Note that the main
inputs may be accepted if IN or IN_LO is not in “Not
Connected” sub-status. In this case, the number of
inputs that are not in “Not Connected” sub-status is
regarded as “N.”
18.4 Output Section
After executing the computing equation, the block
applies a gain to the calculated result and then adds
a bias to it.
It then substitutes the result into PRE_OUT and
if the mode is in AUTO, the value of PRE_OUT is
taken as OUT.
PRE_OUT = func × gain + bias
where func: result of computing equation
execution
OUT = PRE_OUT (when the mode is in AUTO)
Next, the block performs limitation processing
(OUT_HI_LIM, OUT_LOW_LIM). This processing
is described as follows with respect to the value of
PRE_OUT.
If PRE_OUT > OUT_HI_LIM:
PRE_OUT = OUT_HI_LIM
The “high limited” processing is applied to
the status of PRE_OUT.
If PRE_OUT < OUT_LO_LIM:
PRE_OUT = OUT_LO_LIM
The “low limited” processing is applied to the
status of PRE_OUT.
18.4.1 Mode Handling
Mode Output
Auto OUT = PRE_OUT
MAN For OUT, the OUT value in the Auto mode just
before change to MAN or O/S is retained. O/S
In the Manual mode (including O/S), the value of
OUT in the Auto mode just before a change to the
Manual mode is held or the value written to OUT is
output.
If the mode is switched from Manual to Auto, the
value of OUT that is linearly changed with respect to
the value of PRE_OUT for time set by BAL_TIME is
output. The PRE_OUT always indicates the results
of calculation. After elapse of BAL_TIME, OUT =
PRE_OUT is established. Note that if the value
of BAL_TIME is changed during linear change
of the OUT value, it is not reflected. The value of
BAL_TIME will be reflected only after the mode is
changed the next time.