Yokogawa DAQWORX - Manual (Page 58)

2-28 IM WX103-01E
Explanaton
Overvew of Computaton
You can enter computing equations using constants, operators, and functions described
below. The computed results can be displayed and recorded (saved) as computed data.
Computation allows you to determine the average/maximum/minimum of a specified
channel on a specified date/time or output events (start/stop record, reset time, etc.)
under specified conditions. The number of available computation channels is 240, and
the number of characters that can be used in the equation is 127.
Settng the Computaton Span
You can set the span of transmission output for the analog output and PWM output
modules.
Constants
The following three types of constants can be used.
• User Defned Constants
A constant can be assigned to an arbitrary string (name). You can set up to 240 user-
defined constants. Set the Name of the constant using a string (up to 10 characters)
that is not used by predefined constants or functions. They are not case-sensitive.
The precision and range of the constant values are the same as the single-precision
floating point format (32 bits, negative values: -3.4028235E+38 to -1.401298E-45, and
positive values: 1.401298E-45 to 3.4028235E+38).
• Predefned Constants
The five strings below are used for predefined constants. They are not case-sensitive.
• NaN: Represents an invalid value or error value. For a description of the
computed result when NaN is used in the computation, see “Notes on
Computation” in this section.
• POver: Represents +Over (positive overrange). The expression POver > x is
satisfied for any arbitrary value x.
• MOver: Represents –OVER (negative overrange). The expression MOver < x is
satisfied for any arbitrary value x.
• Pi: Represents the ratio of the circumference (3.14...).
• e: Represents the base of the natural logarithm (2.718...).
• Numercal Constants
Numeric values that are written directly in the equation. They are expressed in the
following form.
[digits][.digits][{d|D|e|E}[digits]]
Example: 1.0d+1 represents 10.0.
Channel Numbers
Channel numbers can be used to specify the <channel> (measurement or computation
channels). The channel number is specified using five digits: the unit number is the
highest two digits and the channel number within the unit is the lowest three digits.
Measurement channels are specified using 990001 to 99240.
Tag Numbers
Tag numbers can be used to specify the <channel> (measurement or computation
channels). The tag numbers are enclosed in double quotation marks as in “TagNo.00001”
They are case-sensitive.
Note
If the same tag number is specified on multiple channels, the operation is undefined.
Alarm Level
Use 1 to 4 to specify the level of alarms 1 through 4.
2.5 Settng Computatons (Settng the Computaton Channels)