GET_NAMED_MEMORY_RETAIN block

At present, the GET_NAMED_MEMORY_RETAIN block is analogous to the GET_NAMED_MEMORY block but GET_NAMED_MEMORY_RETAIN returns the reference to a different memory area than GET_NAMED_MEMORY (see "Example with reference to different memory area").

The GET_NAMED_MEMORY_RETAIN block returns the →reference to a →retentive memory area the name of which is entered at input NAME. Use the SAVE_ALL_NAMED_MEMORY_RETAIN block or SAVE_NAMED_MEMORY_RETAIN block in order to save all retentive memory areas or just one to persistent storage.
By default, the appropriate file is saved to the subdirectory PLC of the Neuron RTS max installation directory. If you prefer that a different directory is used, contact your system integrator and ask to change the configuration of the system service.

Short summary

Name	`GET_NAMED_MEMORY_RETAIN`
→POU type	→function
Category	IEC-block, MemoryEnh, block with internal error diagnostic
Conform to →IEC-standard	not defined in IEC-standard
Graphical interface
Available since	version 1.53.0 (for Neuron Power Engineer) and version 3.0.8 or 2.3.1801 of Neuron RTS max This block is supported for the built-in PLC only. version 1.109.0 (for Neuron Power Engineer) and version 3.19.0 of Neuron RTS max: returns the reference to the same memory area as `GET_NAMED_MEMORY` This block is supported for the built-in PLC and the platforms `WindowsX86` and `LinuxX86` only. version 3.2.2 (for library `Standard`) – enhancement: wider interface; returns the reference to a different memory area than `GET_NAMED_MEMORY`

Example with reference to different memory area

The following example contains 2 program instances: one is writing a configuration value into a retentive named memory area, the other is reading it:

CONFIGURATION LocalConfiguration

  RESOURCE local ON BuiltInPlc { ON_CHANNEL := LocalChannel }

    TASK DefaultTask(INTERVAL := TIME#500ms, PRIORITY := 38229);

    PROGRAM ProgramInstance1 WITH DefaultTask :

      Program1;

    PROGRAM ProgramInstance2 WITH DefaultTask :

      Program2;

  END_RESOURCE

END_CONFIGURATION

As Program2 erroneously uses GET_NAMED_MEMORY() to request the named memory area, the returned reference is not as expected:

PROGRAM Program1

VAR

    ReferenceToInteger : REF_TO INT;

  END_VAR

  ReferenceToInteger := GET_NAMED_MEMORY_RETAIN('IntegerBlock');

  IF ReferenceToInteger <> NULL THEN

    ReferenceToInteger^ := 42;

  END_IF;

END_PROGRAM

PROGRAM Program2

VAR

    ReferenceToInteger : REF_TO INT;

  END_VAR

  ReferenceToInteger := GET_NAMED_MEMORY('IntegerBlock');

  IF ReferenceToInteger <> NULL THEN

    /* The following assertion will fail since 'Program2' erroneously requested

     * a named memory block that is NOT retained, thus gets a different block

     * than 'Program1'. For this reason, the value stored in the block is not '42' as

     * expected, but the initial value of zero...

*/

  Assert(ReferenceToInteger^ = 42);

  END_IF;

END_PROGRAM

To fix this issue, you need to replace the call GET_NAMED_MEMORY() by the call GET_NAMED_MEMORY_RETAIN().