Yokogawa DAQWORX Uživatelský manuál stáhnout pdf (Strana 58)

2-28

IM WX103-01E

Explanation

Overview of Computation

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.

Setting the Computation 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 Defined Constants

A constant can be assigned to an arbitrary string (name). You can set up to 240 user-

dened constants. Set the Name of the constant using a string (up to 10 characters)

that is not used by predened constants or functions. They are not case-sensitive.

The precision and range of the constant values are the same as the single-precision

oating point format (32 bits, negative values: -3.4028235E+38 to -1.401298E-45, and

positive values: 1.401298E-45 to 3.4028235E+38).

• Predefined Constants

The ve strings below are used for predened 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 expressi

on POver > x is

satised for any arbitrary value x.

• MOver: Represents –OVER (negative overrange). The expression MOver < x is

satised for any arbitrary value x.

•

Pi: Represents the ratio of the circumference (3.14...).

• e:

Represents the base of the natural logarithm (2.718...).

• Numerical 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 Setting Computations (Setting the Computation Channels)

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