Class - Examples

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Related Links: User Defined Class and Functions, Example PGM Files

Class - Introduction Class - Defining a Class Class - Using a Class Class - Macros Class - Examples

Global Predefined Class Instances: Species Database Class, Particle Size Definition Class, Plant Model Class
Predefined Classes: Array Class, StrArray Class, Matrix Class, TagSelect Class, Noise Class, TimeClass

Declaring Class Instances

; Declare Class instances
	CSTR_Class Tank_A, Tank_B, Tank_C, Tank_D, Tank_E, Tank_F
;-----------------------------------------------------------
;Initialise class instance
	Sub InitialiseSolution()
		ForEachSub(CSTR_Class, Init())
	EndSub
;-----------------------------------------------------------
;Execute CSTR_Class subroutines  
	ForEachSub(CSTR_Class, Exec())

NOTES:

  1. In the above example, we have defined 6 instances of the CSTR_Class.
  2. When a Class instance has been declared, SysCAD will create variables and functions for that instance.
    • For example: For CSTR_Class Tank_C, the following variable and functions can be accessed:
    • String1 = Tank_C.ClassTag() - returns the class instances tag name (in this case, "Tank_C" is returned as a text string variable)
    • String2 = Tank_C.ClassName() - returns the class instance type name (in this case, "CSTR_Class" is returned as a text string variable)
    • Tank_C.UnitTag- This is an example of the class variable.
    • Tank_C.Exec() - This is an example of the class function.
  3. Use ForEachSub(CSTR_Class, Exec()) to call and execute class function/subroutine for all class instances.
    • Exec() is a user defined subroutine in the CSTR_Class (template).

CSTR Tank C.png

Declaring Class Instances in an array

Class instance can also be defined in an array format, for example an equivalent of the above code can be written as:

After Build 139.32530 For earlier builds of SysCAD 
;After {{Available139|32530||y}}
const long TankCount = 7
CSTR_Class Tank[TankCount]{ez}

Sub InitialiseSolution()
    ForEachSub(Tank, Init())
EndSub
 
ForEachSub(Tank, Exec())

long i
const long TankCount = 7
CSTR_Class Tank[TankCount]
ExcludeWatch Tank[0]

Sub InitialiseSolution()
     i = 1
     While (i<TankCount)
         Tank[i].Init()
         i = i + 1
     EndWhile      
EndSub
      
i = 1
While (i<TankCount)
     Tank[i].Exec()
     i = i + 1
EndWhile

NOTES:

  1. Seven CSTR_Class instances are defined here, Tank 0 to Tank 6.
    • The array always starts with 0, therefore, we have intentionally defined 7 instances here and we will use Tanks 1 to 6. In our PGM code we will skip Tank 0 and start with Tank 1.
  2. The ExcludeWatch Keyword instructs SysCAD not to display Tank 0.
  3. The ExcludeClass Keyword instructs SysCAD not to include Tank 0 in any ForEach macro.
  4. If the "Init()" subroutine requires a different input parameter for each call, such as Init("tagname"), then ForEachSub(Tank, Init()) cannot be used.

Using ForEachSub with multiple class declarations

Some Examples on how to use the function:

The following code... Is equivalent to... 
CSTR_Class Tank10, Tank20
CSTR_Class Tank[3]
 
 ;Example 1:
 ;Call Exec for all instances of CSTR_Class
 ForEachSub(CSTR_Class, Exec())
 
 ;Example 2:
 ;Call Exec for all instances in Tank[] Class Array only
 ForEachSub(Tank, Exec())
 
 CSTR_Class  Tank30
  • Note that Tank30.Exec() is not called since Tank30 it is declared after ForEachSub(CSTR_Class, Exec()).
 
CSTR_Class Tank10, Tank20
CSTR_Class Tank[3]
 
 ;Example 1:
 ;Call Exec for all instances of CSTR_Class
 Tank10.Exec()
 Tank20.Exec()
 long i
 i = 0
 While (i<3)
     Tank[i].Exec()
     i = i + 1
 EndWhile
 
 ;Example 2:
 ;Call Exec for all instances in Tank[] Class Array
 i = 0
 While (i<3)
     Tank[i].Exec()
     i = i + 1
 EndWhile
 
CSTR_Class Tank30

Examples Using ClassList

  • Example of define Class instances and Class List Separately:
;define Class instances
TankClass T1,T2,T3,T4,T5
;define the class list
ClassList ABC {T1,T2,T3,T4,T5}
  • Example of defining the ClassList at the same time as the class instances declaration, can use List/L/ClassList
TankClass{List(ABC)}T1,T2,T3
  • Examples of using the ClassList created:
ClassGrid ABC
ForEachSub(ABC, Init())
TotalMass = ForEach(+, ABC, Mass)
  • Other Examples:
ClassList List1 {T1,T2,T3}
ClassList List2 {T4,T5}
ForEachSub(List1, Exec(true))
ForEachSub(List2, Exec(false))

Example using Include File

The user wants to calculate the required agitator power in a number of vessels in a project. This functionality will be used in a number of different projects, and hence the file with the class will be stored on the network where it can be accessed by a number of users and projects.

A formula that may be used to calculate the agitator power for turbulent flow is:

[math]\displaystyle{ \mathbf{\mathit{P = P_o\;N^3\;D^5\;Density}} }[/math]
where:
P - Agitation Power;
Po - the dimensionless power number, which is a function of impeller geometry;
N - agitator rotational speed;
D - Diameter of the impeller;
Density - Density of the material in the vessel.

The class is saved in a file called AgitatorPower.pgm and is saved on the network at n:\Users\SysCAD Common Files\

The Class file is as follows: The main pgm file may have the following structure: 
Class    Class_AgitatorPower
  Textbreak
  ClassGridColumnWidth 12
  ClassGridMaxColumns 5
  TextLabel "Inputs"
  String   UnitName{Tag}*
  real     Po*<<1>>
  real     N<<0.3>>{i, comment("Rotation per second")}
  real     D<<1>>{i, ("L", "m"), comment("ImpellerDiameter")}
  TextLabel "Results"
  string   DensityTag@@{ Tag}
  real     Density@("Rho", "kg/m^3")
  real     Power@("Pwr", "kW")

  Sub Init()
	UnitName = ClassTag()
    DensityTag = Concatenate(UnitName, ".QProd.SLRho (kg/m^3)")
  EndSub

  Sub Exec()
    Density = [DensityTag]
    Power = Po * N^3 * D^5 * Density
  EndSub
EndClass
  • The class instance name is assumed to be the same as the SysCAD unit tag. This is done inside the Sub Init().
 
PageLabel "Agitators" 
>>n:\Users\SysCAD Common Files\AgitatorPower.pgm
Textbreak
;Define class instances in grid format by adding "#"
Class_AgitatorPower # Cementation, NiCo_Precip, Ni_Diss_1

Sub InitialiseSolution()
  ForEachSub(Class_AgitatorPower, Init())
EndSub

ForEachSub(Class_AgitatorPower, Exec())
$ ; --- end of file ---

And the access window of the controller will show the following fields:

Class 1.png

Notes:

  1. The user may follow the same rules for individual functions that may be useful in a number of pgms or in separate projects.

Example Using Class List and Class Macro

>>_Class_BFDFlow.pgm

TextLabel ,"  ============= Block Mass Flow ============="
TextLabel "   == Inputs Streams =="
Class_BFD_Summary #	P101, P709, P412, P102
ClassList Inputs{P101, P709, P412, P102}
TextLabel "   == Outputs Streams =="
Class_BFD_Summary #	P104, P103
ClassList Outputs{P104, P103}
TextLabel "   == Balance =="
Real	Total_Input_Mass@("Qm", "t/h")
Real	Total_Output_Mass@("Qm", "t/h")
Real 	Balance_MassFlow@("Qm", "t/h")

Sub InitialiseSolution()
   ForEachSub(Class_BFD_Summary, init())
EndSub

Sub TerminateSolution()	
    ForEachSub(Class_BFD_Summary, exec())
	Total_Input_Mass  = ForEach(+, Inputs, MassFlow)
	Total_Output_Mass = ForEach(+, Outputs, MassFlow)
	Balance_MassFlow  = Total_Input_Mass - Total_Output_Mass 
EndSub

PGM ClassExample5.png
This example is from the Nickel_Copper_Project, specifically the Cementation_Summary general controller on the Summary flowsheet. The aim is to perform a mass balance across a "process block" using user-specified input and output streams.

Example using TagSelect to initialse UnitTag

>>_Class_TankVol.pgm
;--- variable declarations ---

PageLabel "Tanks"
	TextLabel   "" 
	StrArray 	TankTags
	string 		Tag_Name
	TagSelect 	FindTanks
	Checkbox 	TagListOK@
	Long 		TankTagCount@, i

Class_Tank # Tanks[18]{ez}

Sub PreStart() 
	  TagListOK    = FindTanks.Exec("[UnitType] == 'Tank-1' ", false, false)
	  ; find total number of feeders 
	  TankTagCount = FindTanks.GetLen()
	  TankTags.SetSize(TankTagCount)
	  i=0
	  while (i<TankTagCount)
		  Tag_Name = FindTanks.Tag(i)
		  TankTags.SetAt(i, Tag_Name)
 	  	  Tanks[i+1].UnitTag  = TankTags.GetAt(i)  
		  i = i + 1
	  endwhile
EndSub

Sub InitialiseSolution()
  ;--- Logic executed during initialisation before first iteration
  ;For example to set initial values, or set values in units
  	ForEachSub(Tanks, Init())
EndSub

;--- Logic - executed at EVERY step ---
	ForEachSub(Tanks, Exec())

$ ; --- end of file ---

A variation of this example can be found in Nickel_Copper_Project. This version is slightly simplified. A simplified version of the Tank Volume class can be found on this page: Simple Example.

The aim is to perform the tank volume calculation for all tanks in the project based on user-specified residence time. The class instances are defined as an array. The UnitTag for the class instances will be initialised by Model Tag names in the project. This is done by using the predefined TagSelect Class to search the project for tags matching the "Tank-1" UnitType.

Other PGM Example Files using Classes

There are many example PGM files that use classes, which are listed on this page: PGM Files using Class and Functions

Example User Defined Classes

There are numerous example PGM files in the distributed Example projects that utilise the PGM Class. These are listed on this page: Example User Defined Classes

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