Yokogawa Data Acquisition with PID Control CX2000 - Manual (Page 110)

1-98
IM 04L31A01-01E
1.19 Equations for Control Computation (Style
Number S3 or Later)
PV/SP Computation
When PV and program control function is OFF, you can set an equation for SP of the
loops set to remote SP.
Computation Type
• Measurement computations other than TLOG computations
• CLOG
You can calculate the max value, min value, average, and the difference in the max
and min values of data measured at the same time (max 10 channels). Measurement
data and control input data can be used for this computation.
You can not set an equation inside the CLOG equation.
One CLOG only can be set within the PV/SP equation.
The target data designation is delimited with periods. You can use hyphens to
express a continuous range of channels.
• Conditions
A different computation is performed depending on the computed results of the
specified equation.
For [eq1?eq2:eq3], if the computed result of eq1 is other than 0, eq2 is computed, and
if that result is 0, then eq3 is computed.
You can set a conditional expressions such as [eq1?[eq2-1?eq2-2:eq2-3]:[eq3-1?eq3-
2:eq3-3]].
Equations may not be used simultaneously.
Data That Can Be Used in Equations
The data that can be used in equations is the same data that can be used for the
measurement computation function, plus the following:
• Control input channel data (2 loop models: CI01-CI05, 4 to 6 loop models: CI01-CI10).
• Constants (however W01-W36, and the measurement constants K01-K36 cannot be
used).
• Status of internal switches.
• The status of the control relays (DO001-DO206) and control expansion relays
(RO001-RO012).
Logic Computation
The computed result is output to the DO or internal switch as a 0 or 1.
Computation Type
Computation Type Operator
Logical operation AND, OR, XOR, NOT
Relational operation .GT., .LT., .GE., .LE., .EQ., .NE.
Conditional expressions [eq1?eq2: eq3]
Data That Can Be Used in Equations
Same as for PV/SP computation.
Analog Retransmission
If the control mode is Analog Retransmission, you can set an equation for the control
output.
The data that can be used for the equation and the computation is the same as for the
PV/SP computation.