Appendix 3 meaning and syntax of equations, Appendix 3 – Yokogawa Data Acquisition with PID Control CX2000 User Manual

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App-10

IM 04L31A01-01E

Appendix 3 Meaning and Syntax of Equations

This section explains in detail the meaning and syntax of equations. It is a supplement
to the information covered in “Computation Function” in section 1.18, “Computation and
Report Functions (Option)” and section 1.19, “Equation for Control Computation.”

Four Arithmetic Operations

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.
Equation Examples
• Addition

01+02
(Determines the sum of the measured values of channel 1 and channel 2.)

• Subtraction

01–02
(Determines the difference of the measured values of channel 1 and
channel 2.)

• Multiplication 01*K03

(Multiplies constant K03 to the measured value of channel 1.)

• Division

01/K02
(Divides the measured value of channel 1 by constant K02.)

Note

By setting an equation similar to the one shown below, you can determine the accumulation

of a specified channel (in this case channel 01) and make the result the computed value of

computation channel 31. The computing equation of computation channel 31: 31+01

Power and Other Computations

01**02
(Determines the measured value of channel 1 to the power of the
measured value of channel 2.)

• Square root

SQR(02)
(Determines the square root of the measured value of channel 2.)

• Absolute value

ABS(02)
(Determines the absolute value of the measured value of channel 2.)

• Common logarithm LOG(01)

(Determines the common logarithm (log

) of the measured value of

channel 1.)