Yokogawa Removable Chassis DX1000N - Manual (Page 249)

9-5
IM 04L41B01-01E
Computation and Report Functions (/M1 and /PM1 Options)
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9.2 Writing Expressions
This section explains the meaning and how to write expressions.
Common Items
Follow the rules below when writing expressions.
• Use up to 120 characters to write expressions.
• The precedence of computing terms can be specified using parentheses.
• Specify the channels in the expression using channel numbers.
Example: 1, 12, and 101
• The one-digit number of constants (K), communication input data (C), remote input
terminal status (D), pulse input (P, Q), internal switch (S), alarm output relay status
(I), flag (F), and recording (memory sampling) status (M) in the expression can be
denoted as in “01” and “1.”
Example: K01, K1, C01, C1, D01, D1, P01, P1, Q01, Q1, S01, S1, I01, I1, F01, and F1.
• The data of the previous scan is used in the computation for its own channel number
and channel numbers greater than its own channel number in the expression.
• Special computation (HOLD, RESET, and CARRY) and conditional expressions are
written at the beginning of the expression.
Order of Precedence in Computations
The order of precedence of computation in expressions is as follows:
Type Computing Element
(high order of precedence)
Function ABS(), SQR(), LOG(), LN(), EXP(),
TLOG.MAX(), TLOG.MIN(), TLOG.AVE(),
TLOG.SUM(), TLOG.P-P(), CLOG.MAX(),
CLOG.MIN(), CLOG.AVE(), CLOG.SUM(),
CLOG.P-P()
Special computation and conditional expression PRE, HOLD, RESET, CARRY, [a?b:c]
Power **
Logical negation NOT
Multiplication and division *, /
Addition and subtraction +, –
Greater than and less than .GT., .LT., GE., LE.
Equal and not equal .EQ., .NE.
Logical product AND
Logical sum and exclusive logical sum OR, XOR
(low order of precedence)
Limitations
The following limitations exists in writing expressions.
Type Limitations
TLOG computation A computing element cannot be written inside the parentheses.
Only one TLOG computation can be specified in a single expression.
CLOG computation Number of channels that can be written in the parentheses is 30 channels or less.
A computing element cannot be written inside the parentheses.
Only one CLOG computation can be specified in a single expression.
PRE A computing element cannot be written inside the parentheses.
HOLD(a):b Can only be written at the beginning of an expression.
Only one HOLD computation can be specified in a single expression.
RESET(a):b Can only be written at the beginning of an expression.
Only one RESET computation can be specified in a single expression.
CARRY(a):b Can only be written at the beginning of an expression.
Only one CARRY computation can be specified in a single expression.
Only TLOG.SUM can be written in “b.”
Conditional equation
[a?b:c] RESET, CARRY, or HOLD cannot be written to “a,” “b,” or “c.” Other computing
elements cannot be combined (example: [a?b:c]+001). However, coditional
equations can be specified for a, b, and c.