Yokogawa Data Acquisition with PID Control CX2000 - Manual (Page 380)

App-11
IM 04L31A01-01E
Appendix
App
• Exponent EXP(01)
(Determines e to the power of the measured value of channel 1.)
Note
You can determine the natural logarithm by setting an equation like the following.
From log
b
X = log a X/loga
b
, we obtain log
e
X = log
10
X/log
10
e
Hence, to determine the natural logarithm of channel 1, we set
K01 = 0.43429(log
10
e)
and set the equation to LOG(01)/K01.
Relational Computation
The data that can be used in equations is as follows: measurement data (01-20),
computation data (31-60), control data (101-118, 201-248), constants (K01-K30),
communication input data (C01-C30), remote input status of measurement alarm option
terminal block (DO1-DO8), contact input/output status of control output terminal block
(DI001-DI006, DI101-DI106, DI201-DI206, DO001-DO006, DO101-DO106, DO201-
DO206), contact input/output status of control DIO expansion terminal block (RI001-
RI012, RO001-RO012), control measured data (CI01-CI10), constants control
computation (W01-W36), and status of internal switches (SW01-SW36). See page App-
8 for the data that can be used with control computation and measurement computation.
You can specify a computing equation that performs relational computation on a
computing element. (Example: 01.LT.ABS(02))
Equation Examples
02.LT.03
If the measured value of channel 2 is less than the measured value of channel 3, the
computed result is “1.” Otherwise, the result is “0.”
02.GT.03
If the measured value of channel 2 is greater than the measured value of channel 3, the
computed result is “1.” Otherwise, the result is “0.”
02.EQ.03
If the measured value of channel 2 is equal to the measured value of channel 3, the
computed result is “1.” Otherwise, the result is “0.”
02.NE.03
If the measured value of channel 2 is not equal to the measured value of channel 3, the
computed result is “1.” Otherwise, the result is “0.”
02.GE.03
If the measured value of channel 2 is greater than or equal to the measured value of
channel 3, the computed result is “1.” Otherwise, the result is “0.”
02.LE.03
If the measured value of channel 2 is less than or equal to the measured value of
channel 3, the computed result is “1.” Otherwise, the result is “0.”
Logical Computation
Checks whether the two data values, e1 and e2 (e1 only for NOT), are zeroes or non-
zeroes, and computes according to the conditions. The data that can be used in
equations is as follows: measurement data (01-20), computation data (31-60), control
data (101-118, 201-248), constants (K01-K30), communication input data (C01-C30),
remote input status of measurement alarm option terminal block (DO1-DO8), contact
input/output status of control output terminal block (DI001-DI006, DI101-DI106, DI201-
DI206, DO001-DO006, DO101-DO106, DO201-DO206), contact input/output status of
control DIO expansion terminal block (RI001-RI012, RO001-RO012), control measured
data (CI01-CI10), constants control computation (W01-W36), and status of internal
switches (SW01-SW36). See page App-8 for the data that can be used with control
computation and measurement computation. You can specify a equation that performs
logical computation on a computing element.
Appendix 3 Meaning and Syntax of Equations