Data types

Each variable is based on an IEC data type. The data type consists of the same properties as the variable itself (unit, signal resolution, limit, etc.) with the exception of the driver-specific properties as e.g. the addresses in the PLC. A data type is a variable template without connection to the process. This connection to the process is established with the driver object type for the variable.

On creating a new variable a data type has to be selected. All properties of the data type are inherited to the variable. A reference to the properties of the data type is established, i.e. if a property of the data type is changed, it is also changed in all variables linked to that data type.

If a property is a reference, it is marked with a symbol in the properties window.

This reference can also be cut. A more detailled description can be found in the chapter inheritance concept.

IEC datatypes:

IEC data types are normed in the IEC 61131-3 by the IEC. At the the moment zenon supports the following IEC data types:

Short name	Long name	Comment / value range	Number of bits
BOOL	Boolean	Bit: 0/1	1
BYTE
SINT	Short integer	Signed byte: -128 to 127	8
USINT	Unsigned short integer	Byte: 0 to 255	8
INT	integer	Signed word: -32768 to 32767	16
UINT	Unsigned integer	Word: 0 to 65535	16
DINT	Double integer	Signed double: -2147483648 to 2147483647	32
UDINT	Unsigned double integer	Double: 0 to 4294967295	32
LINT	Long Integer	Because zenon cannot hold the value range of a 64 bit number, the actual value range is restricted to 52 bits. Numbers with signs are possible from –2251799813685248 to 2251799813685247. Numbers outside of this range cause a overflow or underflow, according to a 52-bit integer. The following components work with a full 64 bit resolution in the zenon Runtime: The shared memory VBA Interface, when the value was entered in signal resolution. The shared memory straton interface. The driver kit works for the whole range of 64 bits, and so do all the drivers, provided the driver supports this data type. At the moment, these are Sample32, Internal and STRATON32. RGM and recipes cannot save even a 52 bit value with full accuracy.	64 resp. 52
ULINT	Unsigned long integer	Because zenon cannot hold the value range of a 64 bit number, the actual value range is restricted to 52 bits. Numbers without signs are possible from 0 to 4503599627370496. Numbers outside of this range cause a overflow or underflow, according to a 52-bit integer. The following components work with a full 64 bit resolution in the zenon Runtime: The shared memory VBA Interface, when the value was entered in signal resolution. The shared memory straton interface. The driver kit works for the whole range of 64 bits, and so do all the drivers, provided the driver supports this data type. At the moment, these are Sample32, Internal and STRATON32. RGM and recipes cannot save even a 52 bit value with full accuracy.	64 resp. 52
REAL	Real numbers	Real numbers	32
LREAL	Real numbers	Real numbers	64
STRING	Variable-length single byte character string	ASCII string (the max. string length depends on the driver). The string length is set to 5 as a default. If needed the length has to be changed.

Refer to the chapter Inheritance concept for the detailed description of the inheritance of data type properties.