Pointers

Pointers are represented by the DynamicPointerInstance class. Like other symbols, you can access or modify their raw values using the ReadValue() and WriteValue(Object) methods.

For safety, avoid using raw pointers. In practice, you typically care about the data a pointer references, not the pointer itself.

You can access the referenced data using the Reference property, which returns a DynamicSymbol instance. This allows you to read or write data normally, as described in the previous or following sections.

Reading Pointer Values

dynamic MAIN = symbols["MAIN"];
double plcDblValue = MAIN.pValue.Reference.ReadValue();

Writing Pointer Values

MAIN.pValue.Reference.WriteValue(6.626);

Advanced Pointer Usage

For a self-referential struct like the following:

TYPE ST_Node:
STRUCT
    arData  : ARRAY[0..3] OF ARRAY[0..3] OF ST_Data;
    pNext   : POINTER TO ST_Node;
END_STRUCT
END_TYPE

PROGRAM MAIN
VAR
    stNode : ST_Node := (pNext := ADR(stNode));
END_VAR

You can access the current node’s data and the next node’s data using the Reference property:

dynamic MAIN = symbols["MAIN"];

// Access the current node’s data
dynamic current = MAIN.stNode.ReadValue();
Console.WriteLine(JsonConvert.SerializeObject(current.arData));

// Access the next node’s data
dynamic next = MAIN.stNode.pNext.Reference.ReadValue();
Console.WriteLine(JsonConvert.SerializeObject(next.arData));