Owner's manual

4-3
Arithmetic Function Block
Figure 4-2. Signal Characterizer
Function Block Schematic Diagram
Block Execution The Arithmetic function block provides range extension and
compensation through nine (9) arithmetic types.
There are two inputs (IN and IN_LO) used in calculating PV. PV is then
combined with up to three inputs (IN_1, IN_2, and IN_3) through the
user selected compensation function (ARITH_TYPE) to calculate the
value of func. A gain is applied to func and then a bias is added to get
the value PRE_OUT. In AUTO, PRE_OUT is used for OUT.
Range Extension and
Calculation of PV
When both IN and IN_LO are usable, the following formula is applied to
calculate range extension for PV:
G has a range from 0 to 1, for IN from RANGE_LO to RANGE_HI.
Compensation Input
Calculations
For each of the inputs IN_1, IN_3, IN_4 there is a gain and bias. The
compensation terms (t) are calculated as follows:
• When IN_(k) is usable:
• When IN_(k) is not usable, then t(k) gets the value of the last t(k)
computed with a usable input.
FBUS_49A
RANGE_LO
RANGE_HI
PV_UNIT
PV
ARITH_TYPE
BAL_TIME
GAIN + BIAS
OUT_HI_LIM
OUT_LO_LIM
OUT_LO_LIM
OUT_LO_LIM
tempIN_1
(IN_1 + BIAS_IN_1) * GAIN_IN_1
IN_1
IN_2
IN_3
IN
IN_LO
tempIN_2
tempIN_3
ALGORITHM
LOGIC
Range
Extension
Function
(IN_2 + BIAS_IN_1) * GAIN_IN_2
(IN_3 + BIAS_IN_1) * GAIN_IN_3
PV G IN• 1G–()IN_LO•+=
t(k) GAIN_IN(k) BIAS_IN(k) IN_(k)+()•=