Object

(TcoObject : ITcoObject)

API

TcoObject provides access to :

  • Context
  • Reference to the parent object
  • [Identity] (unique identifier across application)
  • Access to a messaging system
  • and other useful functions. (e.g. RTC)

Each block in TcOpen framework should derive from TcoObject.

If we stretch our imagination, we can think of TcoObject as object in C# (all objects derive from System.Object);

TcoObject construction (FB_init)

TcoObject must be constructed via FB_init method passing in a parameter of parent ITcoObject; that is usualy another TcoObject or a TcoContext eventualy other type that implements ITcoObject interface.

As a rule, all objects should be constructed as follows:

FB_init when object is in another FUNCTION_BLOCK

FUNCTION_BLOCK myFunctionBlock : EXTENDS TcoCore.TcoObject
VAR
    myObject : MyTcoObject(THIS^);
    
END_VAR

where THIS^ is of ITcoObject.

FB_init when object is in another STRUCTURE

TYPE
    MyStructure EXTENDS TcoCore.TcoStruct :
    STRUCT
        // Before not possible         
        // Now
        myObject : MyTcoObject(THISSTRUCT);
    END_STRUCT
END_TYPE

where data structure must be initialized within an function block of TcoObject type in the following way:

Data : ExampleInspectorsStruct := (Parent := THIS^);

IMPORTANT!!! The compiler will not warn you missing parent assignment in structure declaration. Missing parent assignment may result in invalid pointer/reference exceptions.

Messenger

API

Any TcoObject can post messages of different severity ulterior use in higher-level applications (HMI/SCADA).

Each TcoObject contains a single message holder Mime or Most Important Message.

The message will be replaced by another message only when the incoming message is of higher severity.

The persistence of the message is within the cycle in which it was created. More about messaging here

An example implementation of station object with messaging

FUNCTION_BLOCK Station001 EXTENDS TcoCore.TcoObject

METHOD CheckStationsSensors()
//------------------------------
Messenger.Debug(CONCAT('Checking stations sesnors, context cycle ', ULINT_TO_STRING(Context.StartCycleCount));
Messenger.Debug(DT_TO_STRING(Context.Rtc.NowLocal()));

IF(failed) THEN
    // This message will appear as MIME (Most important message on the object Station001)
   Messenger.Error('Some sensor just failed'); 
END_IF;