9 Definition of Ctrl Variable Attributes and Properties ToC Previous Next

9.2 DataType ToC Previous Next

9.2.1 Mapping of elementary data types ToC Previous Next

The mapping of IEC 61131-3 elementary data types to OPC UA data types is formally defined in Table 27. The OPC UA built in data types are used for the wire representation of the data type. Additional PLCopen specific OPC UA data type definitions are used to provide the special semantic if necessary.

Table 27 – Mapping IEC 61131-3 elementary data types to OPC UA built in data types

No. IEC 61131-3
elementary data types (Keyword / Description)
DataType NodeID OPC UA
built in data types
PLCopen specific OPC UA simple data type definitions Comment
1 BOOL / Boolean -– Boolean (UA:1) - A one bit value (true or false).
2 SINT / Short integer -– SByte (UA:2) - An 8 bit signed integer value.
3 INT / Integer -– Int16 (UA:4) - A 16 bit signed integer value.
4 DINT -– Int32 (UA:6) - A 32 bit signed integer value.
5 LINT / Long integer -– Int64 (UA:8) - A 64 bit signed integer value.
6 USINT / Unsigned short integer -– Byte (UA:3) - An 8 bit unsigned integer value.
7 UINT / Unsinged integer -– UInt16 (UA:5) - A 16 bit unsigned integer value.
8 UDINT / Unsigned double integer -– UInt32 (UA:7) - A 32 bit unsigned integer value.
9 ULINT / Unsigned long integer -– UInt64 (UA:9) - A 64 bit unsigned integer value.
10 REAL / Real numbers -– Float (UA:10) - OPC UA definition: An IEEE-754 single precision (32 bit) floating point value.
IEC 61131-3 definition: Real (32 bit) with a range of values as defined in IEC 60559 for the basic single width floating-point format.
Both standards are identical.
11 LREAL / Long reals -– Double (UA:11) - OPC UA definition: An IEEE-754 double precision (64 bit) floating point value.
IEC 61131-3 definition: Long real (64 bit) with a range of values as defined in IEC 60559 for the basic double width floating-point format.
Both standards are identical.
12a TIME / Duration x:3005 Int64 (UA:8) TIME The OPC UA simple data type TIME/Duration is derived from the built-in data type Int64. It describes that the type is used as interval of time in milliseconds. The range of valid values is vendor specific.
12b LTIME / Duration x:3006 Int64 (UA:8) LTIME The PLCopen simple data type LTIME is derived from the build in data type Int64. It describes that the type is used as interval of time in nanoseconds. The valid range is LT#-106751d23h47m16s854ms775us808ns to LT#+106751d23h47m16s854ms775us807ns. The representation contains information for days (d), hours (h), minutes (m), seconds (s) milliseconds (ms), microseconds (us) and nanoseconds (ns).
13a DATE / Date (only) x:3007 DateTime (UA:13) DATE The PLC open specific OPC UA simple data type DATE is derived from the built-in data type DateTime. It describes that the type is used as a date only.
13b LDATE / Long date (only) X:3014 Int64 (UA:8) LDATE The PLCopen specific OPC UA simple data type LDATE is derived from the built-in data type Int64. It describes that the type is used as date only. The interval is nanoseconds since 1970-01-01.
14a TOD Time of day (only) x:3008 UInt32 (UA:7) TOD TOD (TIME_OF_DAY) stores number of milliseconds since the beginning of the day: TOD#00:00:00.000 to TOD#23:59:59.999.
14b LTOD (Time of day) x:3009 Int64 (UA:8) LTOD LTOD (LTIME_OF_DAY) stores the number of nanoseconds since the beginning of the day: LTOD#00:00:00.000000000 to LTOD#23:59:59.999999999.
15a DT Date and time of day x:3010 DateTime (UA:13) DT The range and resolution of this type is vendor specific.
15b LDT Date and time of day x:3015 Int64 (UA:8) LDT The PLCopen specific OPC UA Simple datatype LDT is derived from the build in data type Int64. It describes the number of nanoseconds elapsed since 1970-01-01-00:00:00
16a STRING variable-length single-byte character string x:3013 String (UA:12) STRING The PLC open specific OPC UA simple data type STRING is derived from the built-in data type String. It describes that the type is used as a variable-length single-byte character string.
16b WSTRING variable-length double-byte character string -– String (UA:12) - OPC UA definition: A sequence of UTF8 characters.
IEC 61131-3 definition: Variable-length double-byte character string
17a CHAR single-byte character x:3011 Byte (UA:3) CHAR The PLC open specific OPC UA simple data type CHAR is derived from the built-in data type Byte. It describes that the type is used as single-byte character
17b WCHAR double-byte character x:3012 UInt16 WCHAR The PLC open specific OPC UA simple data type WCHAR is derived from the built-in data type UInt16. It describes that the type is used as double-byte character.
18 BYTE Bit string of length 8 x:3001 Byte BYTE The PLC open specific OPC UA simple data type BYTE is derived from the built-in data type Byte. It describes that the type is used as bit string of length 8.
19 WORD Bit string of length 16 x:3002 UInt16 WORD The PLC open specific OPC UA simple data type WORD is derived from the built-in data type UInt16. It describes that the type is used as bit string of length 16
20 DWORD Bit string of length 32 x:3003

   
UInt32 DWORD The PLC open specific OPC UA simple data type DWORD is derived from the built-in data type UInt32. It describes that the type is used as bit string of length 32
21 LWORD Bit string of length 64 x:3004 UInt64 LWORD The PLC open specific OPC UA simple data type LWORD is derived from the built-in data type UInt64. It describes that the type is used as bit string of length 64

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