structured variable as property

2020-02-27T14:23:58.175000Z

Originally created by: scott_cunningham

Properties are like a special get method or set method. They actually run as code when you call them (you can see when you online debug and step through).

I would probably avoid using properties for HMI use - I typically define a structure T_HMI and list out the variables I am transferring and the. Have one program that copies speaking variables from different parts of the program into the one structure. Use VAR ins/outs and inOuts for linking to HMIs.

I typically define the HMI structure as global and then in my FBs that either give or receive data from the HMI, I define REFERENCE TOs on var ins, car outs or var inouts. Then I set the reference to the element in the global structure.

But that is, of course, only my way of doing things.

structured variable as property

2020-02-27T14:23:56.980000Z

So if I understand correctly, a property isn't initialized until it is called from somewhere outside the function block in which it resides. If that's the case I might have to revise my design, as a lot of the status variable properties are strictly for display on an HMI.

structured variable as property

2020-02-27T14:23:56.511000Z

Originally created by: scott_cunningham

Have you called the property? The code doesn't run (i.e. Status is referring to nothing until you call it!). Also, I get a program exception as soon as a assign the attribute monitor to the property (probably because it is not initialized to refer to anything).

I duplicated your project and it is working (I forced some values into _Status):

PROGRAM PLC_PRG
VAR
   Test : MyFbWithRef;
   Res : T_STRUCT;
END_VAR
Res := Test.Status;

FUNCTION_BLOCK MyFbWithRef
VAR
   _Status : T_STRUCT;
END_VAR
PROPERTY Status : REFERENCE TO T_STRUCT
(GET)
Status REF= _Status;

TYPE T_STRUCT :
STRUCT
   Status1: INT;
   Status2: BOOL;
END_STRUCT
END_TYPE

Here is my result:

structured variable as property

2020-02-27T14:23:56.085000Z

I've been trying to define a property as a structured variable. It seems that it's not possible to do it directly (see l viewtopic.php?t=5577 l ), so I followed the advice in that thread and used a reference. That appears to work as far as programming and compiling goes, however, I'm not seeing the variables when I go online with the controller. The little + sign is there, but when I click on it it disappears, and there's no variables. I've used both {attribute 'monitoring':='variable'} and {attribute 'monitoring':='call'}. "variable" will crash the controller with some of the larger structures.

TYPE STRUCTUREDVARIABLE :
STRUCT
   Status1: INT;
   Status2: BOOL;
END_STRUCT
END_TYPE
{attribute 'monitoring':='variable'}
PROPERTY Status : REFERENCE TO STRUCTUREDVARIABLE
(Get)
Status REF= _Status;
FUNCTION_BLOCK TestPOU
VAR
   _Status: STRUCTUREDVARIABLE;
END_VAR

Recent posts to structured variable as property

structured variable as property

structured variable as property

structured variable as property

structured variable as property