Data Types

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PGM Syntax	Data Types	Declaring Variables	Predefined Variables	Formatting

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Summary Table of Data Types

The variable types supported by the PGM are shown below. See also Variable declaration.

Type Name	Value Type	Range of Values	Displayed As	Notes
Real Numbers
REAL	Real	-1.0 E308 to 1.0 E308	Value with decimal points, or * if NAN	Use IsNAN function to test for NAN
DOUBLE	Real	-1.0 E308 to 1.0 E308	Value with decimal points, or * if NAN	Use IsNAN function to test for NAN
Integers
INTEGER	Integer	-2147483648 to 2147483647	Integer
LONG	Integer	-2147483648 to 2147483647	Integer
INT	Integer	-2147483648 to 2147483647	Integer	Available from Build 139.32217.
BYTE	Integer	0 to 255	Integer
Enum	Integer	Usually starts at 0	Creates a list of integer constants.
EnumDropList	Integer	Usually starts at 0	A drop down list with enum list of integer constants.
DropList	Integer	Usually starts at 0	A drop down list, each with an associated integer value
Boolean Numbers
BIT	Boolean	FALSE = 0; TRUE <> 0	0 (False); 1 (True)
BOOL	Boolean	FALSE = 0; TRUE <> 0	0 (False); 1 (True)	Available from Build 139.32217.
BOOLEAN	Boolean	FALSE = 0; TRUE <> 0	0 (False); 1 (True)	Available from Build 139.32217.
CheckBox	Boolean	FALSE = 0; TRUE <> 0	Tickbox
Alphanumeric Values, or Strings
STRING	String	ASCII Character Set;	Words (unlimited length)
STR	String	ASCII Character Set;	Words (unlimited length)
MEMO	String	ASCII Character Set;	Words (unlimited length)	Scrolls onto multiple lines as required

Notes:

1. Variable names must be alphanumeric and uniquely declared within their current scope. See Variable Declaration Rules for a full description.
2. The PGM language, including variable naming, is NOT case sensitive.
3. Only variables of type Double or Real can have a value of NAN (Not a Number) shown as a '*' on the Access window. Use IsNAN function to test for NAN.
4. When a value or variable is assigned to another variable, it is ranged within the new variable type's range, as illustrated in the examples below.

Examples (showing ranging based on Data Type)

INTEGER  w
BIT      i
BYTE     z

z = 1035    ;z = 255         maximum value of Byte type is 255.
z = -2.3    ;z = 0           minimum value of Byte type is 0.
z = 5.6     ;z = 5           byte can only be integer, it takes the first digit
w = 1.3e12  ;w = 2147483647  maximum value of Long type
w = NAN     ;w = -2147483648 not a number, assigned with the minimum value of type
w = 335.4   ;w = 335         INTEGER type are integers only.
z = w       ;z = 255         limited by the maximum value of byte type.
i = 0.1     ;i = 1 (true)    Bit is true if i ≠ 0
i = 12      ;i = 1 (true)    Bit is true if i ≠ 0
i = -3      ;i = 1 (true)    Bit is true if i ≠ 0
i = 0.0     ;i = 0 (false)   Bit is false if i = 0

User Defined Constants using the Const Keyword

Syntax:

Const TYPE variable = value OR

Const TYPE variable = Predefined Molecular Weight Function

A const Array, Matrix or StrArray class can also be declared. Available from Build 139.32335. For example:

const Array SomePrimes = {2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71}
const Matrix Table1 = { {2, 5, 10}, {1, 3, 6} }
const StrArray Rainbow = { "Red", "Orange", "Yellow", "Green", "Blue", "Indigo", "Violet" }

The Const keyword ensures that the value assigned to the variable will remain unchanged (i.e. it becomes a read only variable). See also Predefined Constants and Variables.

Examples

Const real OreDensity = 5000
Const real LiquidHTC  = 1.5    ;Numbers cannot be written as a fraction.

Const real MW_NaCl    = MW("NaCl") 
Const real MW_H2SO4   = MW("H2SO4") 

Const integer Auto    = 1
Const long    Manual  = 2

Const bit Running     = 1
Const bit Stopped     = 0

Const String Condition1 = "Mass balanced"
Const String Condition2 = "Mass NOT balanced"

const real MaxFlow@ = 1300  ; available in Build 139.32530 or later, allows use of @ or @@ when declaring const variables.

NOTES:

1. A Constant variable is always added to global scope even if it is declared within a function or class function. It is accessible in code outside of the function where the const was declared.
2. A Constant variable cannot be declared in a Class.
3. A Constant variable can be displayed in the Access window using Watch.
4. A Constant variable cannot be a calculation, this includes using numbers in fractions. So while const Real LiquidHTC = 1.5 will work, LiquidHTC = 3/2 will report an error.
5. Constant variables cannot be changed, so they can only be appended with @ or @@ when declaring const variables. Available from Build 139.32530.

Check Box

The user can add a check box to the access window by declaring the variable as type Checkbox. The check box is a toggle between true(1) and false(0).

See Declaring Variables.

Integer variables as Enum

An Enum (derived from Enumerate) is an Integer (or Long) data type. The use of Enum is a convenient method to declare a number of integer constants by name. Then use these named constants throughout the code instead of integer values. Code is then significantly easier to follow and maintain.

Note:

1. The user cannot display the Enum constants in the Access window.
2. The names in the Enum list need to be globally unique.
3. The declaration cannot occur within a class, but the declared constants can be used within a class. (See Example : using Enum Drop list and Drop List in a class)
4. As Enum types are simply a synonym for data type Integer. This allows you to declare variables with the named enum type, see definition of Colour_Choice in example.
5. As the underlying data type is simply an integer, there is no enforced validation of the integer value to be limited to the available values in enum list. Use EnumDropList for this purpose.

Example 1: Enum Colours{Red, Green, Blue} Colours Colour_Choice Colour_Choice = Green		This is equivalent to: const integer Red = 0 const integer Green = 1 const integer Blue = 2 Integer Colour_Choice Colour_Choice = Green
Counting is automatic, starting at 0 and incrementing by 1. However, the user may override the automatic values and assign their own values to the variables.

Example 2: Enum Shapes{Square = 2, Circle = 4, Oval, Triangle = 9} Integer Shape_Choice Shape_Choice = Circle

This is equivalent to: const integer Square = 2 const integer Circle = 4 const integer Oval = 5 const integer Triangle = 9 Integer Shape_Choice Shape_Choice = Circle

Enum Drop Down List

The user can add a Drop Down List to the access window by declaring a variable of type EnumDropList. In addition to creating the drop down list the variables are also constant enum integers. The use of named constants throughout the code instead of integer values, makes the PGM code significantly easier to follow and maintain. The use of an EnumDropList is best shown in an example:

Enum Drop Down List Example EnumDropList Options{Acid=2, Basic=4, Neutral} Options Act_Mode@, Req_Mode* string ModeDesc@ Act_Mode = Basic ModeDesc = StrCat("Mixture mode is ", EnumStr(Act_Mode)) if (Act_Mode==Neutral) ;Some code here endif

This will be displayed in the Access window as follows:

Notes:

1. The initial (default) value of the variable is the first item in the list. In the above example Req_Mode will initially be 2 (Acid).
2. Unlike the simple Enum declaration, if the variable is set to a value which doesn't match one of the defined options, SysCAD will choose the option which is numerically the closest.
   • In the above example, if Act_Mode is set to 3, SysCAD will reset its value to 2 (Acid).
3. Each item in the EnumDropList has an integer value.
   • The names in the EnumDropList list need to be globally unique.
   • If the user does not set a value, then counting is automatic, starting at 0 and incrementing by 1.
   • However, the user may override the automatic values and assign their own values to the variables, as shown in the above example. In this case, if a variable is NOT assigned a value, then its value is incremented by 1 from the previous variable.
4. The EnumStr function can be used to return the current value of the variable as a string. Useful for feedback messages, etc.
5. The definition of the drop-down list (using data type EnumDropList) cannot occur within a class, but EnumDropList defined outside of the class can be used for variable declaration within a class. See Example : using Enum Drop list and Drop List in a class.

Drop Down List

The user can add a Drop Down List to the access window by declaring a variable of type DropList. It is more common to use EnumDropList. The variable will be of type Integer. (Note that Enum Drop Down List allows the user to override the automatic sequential values and assign their own values to the variables, whereas Drop Down List variables will always be an integer value starting at 0 and incrementing by 1). Drop Down List is best shown in an example:

Drop Down List Example DropList Options{"Acid", "Basic", "Neutral"} Options Act_Mode@, Req_Mode* Act_Mode = 1 if (Act_Mode==2) ;Some code here endif

This will be displayed in the Access window as follows:

Notes:

1. Each item shown in the Drop Down List has an integer value starting at 0 and incrementing.
   • In the image above, if the user selects 'Acid' in the Req_Mode droplist, then Req_Mode = 0, if 'Basic' is selected, then Req_Mode = 1 and similarly if 'Neutral' is selected, then Req_Mode = 2.
   • Please note that when using the drop list in the PGM logic, user cannot use the string, e.g.: "Act_Mode = Acid", the integer should be used, e.g.: "Act_Mode = 0". To use "Act_Mode = Acid", then the droplist must be defined as 'EnumDropList'.
2. The initial (default) value of the variable is 0, corresponding to Acid, the first item in the list.
   • User can also override the values, see example below
3. If the variable is set to a value which doesn't match one of the defined options, SysCAD will choose the option which is numerically the closest.
   • In the above example, if Req_Mode is set to 4, SysCAD will reset its value to 2 (Neutral).
4. The definition of the drop-down list (using data type DropList) cannot occur within a class, but DropList defined outside of the class can be used for variable declaration within a class. See example below.

Example : using Enum Drop list and Drop List in a class

This example shows the difference in Droplist and EnumDropList definition and usage. In general, the EnumDropList is commonly used.

 
DropList UnitOp{"Ready"=1, "InUse"=4, "Fault"=7, "Maint_Shutdown"=8} ;text strings are enclosed in double quotes, user defined integer values are optional
;DropList UnitOp{"Ready", "InUse", "Fault", "Maint_Shutdown"}  
EnumDropList EnumUnitOp{Ready=1, InUse=4, Fault=7, Maint_Shutdown=8} ;text strings do not have quotes, user defined integer values are optional
;EnumDropList EnumUnitOp{Ready, InUse, Fault, Maint_Shutdown}  

Class Class_EvalPlant
;using pre-defined DropList
  UnitOp        Unit_Operation_State@
  EnumUnitOp    Unit_Operation_State_Enum1@, Unit_Operation_State_Enum2@
  string        State_Description1@,State_Description2@
;place code here
EndClass

PageLabel "UnitOp" 
  TextBreak
  Class_EvalPlant Tank1

  ;Using DropList options - integer value is required
  Tank1.Unit_Operation_State = 7
  ;Using EnumDropList Options, string or integer can be used 
  Tank1.Unit_Operation_State_Enum1 = Maint_Shutdown  ;OR
  Tank1.Unit_Operation_State_Enum2 = 4
  Tank1.State_Description1 = Concatenate("Current state is ", EnumStr(Tank1.Unit_Operation_State_Enum1))
  Tank1.State_Description2 = Concatenate("Current state is ", EnumStr(Tank1.Unit_Operation_State_Enum2))
$

The left image shows the drop-down list using user defined integer values (from the above example), the right image shows the drop-down list using default values (no user value defined when declaring the droplist (as per line 2 and 4 in the above example, these were shown as comments, not in use).