ACR Electronics SmartReader Plus Manual do Utilizador descarregar pdf (Página 141)

Equations

130

2005 ACR Systems Inc.

7.8 APPENDIX A Equation Language

Equation Language

7.8.1 Equation Language Introduction

Equations in

TrendReader Standard 2

use the VB.Net language. Therefore, any code in an

equation must be compliant with the syntax of VB.Net. Although the equation script is VB.Net

compliant, you cannot use all VB.Net methods and functions because some method related

references may not be added to the equation project. Currently, all equation projects have

Microsoft.VisualBasic

and

System

references imported, so any functionality and definitions

under these two references can be implemented. For detailed information please refer to

VB.Net documentation.

An equation is a block of code, formatted in the VB.Net language, that is saved in the system

database with a unique ID. Prior to the execution of the equation, it is compiled into a dynamic

link library (dll) and instantiated as an executable object.

A standard equation looks like:

Sub

EQN101( )

'Calculate engineering value from [1] 8bit Logger-> [0] Any Channel-> [38] 8bit

Raw Value

Dim

Double

Eqn ("CF717AC31D0B479c94AD902D349BDF20", X)

ANSWER0= 2 + 2*X

'Convert user selected subunit to default subunit

ANSWER0=(ANSWER0-0)/1000

End

Sub

EQN101( ) and

End

These lines denote the start and end of the equation code.

Dim

Double

This line declares a variable X to be used in the code.

Eqn ("CF717AC31D0B479c94AD902D349BDF20", X)

This line calculates the engineering value of the current reading from the logger using

another equation and assigns it to the variable X. The equation is identified using a

unique ID -- "CF717AC31D0B479c94AD902D349BDF20". This type of statement is used

when you need to use the engineering value for the reading in your equation. For

example, if you had a transducer that output a voltage proportional to pressure, you would

typically use the voltage channel. To calculate the pressure, you would first need to

convert the data logger reading into a voltage using such a statement. To call another

equation in your code, click the "

Insert Equation

" button and select the equation from the

pop up window.

ANSWER0 = 2 + 2*X

The result of your equation must be assigned to ANSWER0 in the line just before

'== end

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