IEC 61131-3

• Ladder diagram, graphical
• Function block diagram, graphical
• Structured text, textual
• Instruction list, textual
• Sequential function chart, has elements to organize programs for sequential and parallel control processing, graphical.

  Data types

• Elementary Data Type
• * Bit Strings – groups of on/off values
• ** BYTE – 8 bit
• ** WORD – 16 bit
• ** DWORD – 32 bit
• ** LWORD – 64 bit
• * INTEGER – whole numbers
• ** SINT – signed short integer
• ** INT – signed integer
• ** DINT – signed double integer
• ** LINT – signed long integer
• ** USINT – Unsigned short integer
• ** UINT – Unsigned integer
• ** UDINT – Unsigned double integer
• ** ULINT – Unsigned long integer
• * REAL – floating point IEC 60559
• ** REAL –
• ** LREAL –
• *Duration
• ** TIME –. Literals in the form of T#5m90s15ms
• ** LTIME –. Literals extend to nanoseconds in the form of T#5m90s15ms542us15ns
• * Date
• ** DATE – calendar date
• ** LDATE – calendar date
• * Time of day
• ** TIME_OF_DAY / TOD – clock time
• ** LTIME_OF_DAY / LTOD – clock time
• * Date and time of Day
• ** DATE_AND_TIME / DT – time and date
• ** LDATE_AND_TIME / LDT – time and date
• * Character / Character string
• ** CHAR – Single-byte character
• ** WCHAR – Double-byte character
• ** STRING – Variable-length single-byte character string. Literals specified with single quote, 'This is a STRING Literal'
• ** WSTRING – Variable-length double-byte character string. Literals specified with a double quote, "This is a WSTRING Literal"

• Generic Data Types – Only available for the input / output/ in-out variables of system-defined Program Organization Units
• * ANY
• ** ANY_DERIVED
• ** ANY_ELEMENTARY
• *** ANY_MAGNITUDE
• **** ANY_NUM
• ***** ANY_REAL: LREAL, REAL
• ***** ANY_INT
• ****** ANY_UNSIGNED: ULINT, UDINT, UINT, USINT
• ****** ANY_SIGNED: LINT, DINT, INT, SINT
• **** ANY_DURATION: TIME, LTIME
• *** ANY_BIT: LWORD, DWORD, WORD, BYTE, BOOL
• *** ANY_CHARS
• **** ANY_STRING: STRING, WSTRING
• **** ANY_CHAR: CHAR, WCHAR
• *** ANY_DATE: DATE_AND_TIME, DATE_AND_TIME, DATE, TIME_OF_DAY, LTIME_OF_DAY
• User-defined Data Types
• * Enumerated data type
• * Enumerated data type with named value
• * Subrange data type – puts limits on value i.e., INT for current
• * Array data type – multiple values stored in the same variable.
• * Structured data type – composite of several variables and types.
• * Directly derived data type – type derived from one of the above types to give new name and initial value as a type.
• * References – a kind of strongly typed pointer. Arithmetic operation of the value of this type is prohibited.

  Variables

• Global
• Direct
• I/O Mapping – Input, Output, I/O
• External
• Temporary

  Configuration

• Resource – Like a CPU
• Tasks – Can be multiple per CPU.
• Programs – Can be executed once, on a timer, on an event.

  Program organization unit (POU)

• Functions
• * Standard: ADD, SQRT, SIN, COS, GT, MIN, MAX, AND, OR, etc.
• * Custom
• Function Blocks
• * Standard:
• * Custom – Libraries of functions can be supplied by a vendor or third party.
• Programs

  Configuration, resources, tasks

• Configuration – processing resources, memory for IO, execution rates, number of tasks.

  Object oriented programming (OOP)

• The 3rd revision of the standard describes how to implement OOP within the application programming