PLC Programming

Global Variables, Variable Configuration, Document Frame
Editing Remanent Global Variables Lists
If they are supported by the runtime system, remanent variables may be processed. There are two
types of remanent global variables:
Retain variables remain unchanged after an uncontrolled shutdown of the runtime system (off/on) or
an 'Online' 'Reset' in CoDeSys. Persistent variables remain unchanged after a controlled shutdown
of the runtime system (stop, start) or an 'Online' 'Cold reset' or a download.
Persistent variables are not automatically also Retain variables !
Remanent variables are additionally assigned the keyword RETAIN or PERSISTENT.
Network variables are also defined in this syntax.
Syntax:
VAR_GLOBAL RETAIN
(* Variables declarations *)
END_VAR
VAR_GLOBAL PERSISTENT
(* Variables declarations *)
END_VAR
Global Constants
Network variables (target specific) are also defined using this syntax.
Global constants additionally get the keyword CONSTANT.
Syntax:
VAR_GLOBAL CONSTANT
(* Variables declarations *)
END_VAR
6.2.2 Variable Configuration...
In function blocks it is possible to specify addresses for inputs and outputs that are not completely
defined, if you put the variable definitions between the key words VAR and END_VAR. Addresses not
completely defined are identified with an asterisk.
Example:
FUNCTION_BLOCK locio
6-6 CoDeSys V2.3