STVariable is a structure defined by:
Name |
Type Name |
Description |
|---|---|---|
etNodeDataType |
BYTE |
A user–defined variable type. |
pbyBuffer |
REF_TO ANY |
Reference to application variable. |
etNodeDataType
Configure etNodeDataType with an OPC UA build-in data type. See the OPC UA Online Reference at:
https://reference.opcfoundation.org/v104/Core/docs/Part6/5.1.2/
The following OPC variable types correspond to the IEC 61131-3 data types:
Type |
Value |
Description |
|---|---|---|
UATypeNull |
0 |
- |
UATypeBool |
1 |
BOOL |
UATypeSByte |
2 |
|
UATypeByte |
3 |
BYTE |
UATypeInt16 |
4 |
INT |
UATypeUInt16 |
5 |
UINT |
UATypeInt32 |
6 |
DINT |
UATypeUInt32 |
7 |
UDINT |
UATypeInt64 |
8 |
|
UATypeUInt64 |
9 |
|
UATypeFloat |
10 |
REAL |
UATypeDouble |
11 |
|
UATypeString |
12 |
STRING (in this case the code resolves the shorted size between source and destination variable) |
UATypeDateTime |
13 |
DT NOTE: The DT format is server dependent. For example, some servers can
return:
|
| CAUTION | |
|---|---|
UNEXPECTED BEHAVIOR OF APPLICATION Verify that the type of variables selected for local variables
(parameter VARIABLES for UA_ReadList, UA_WriteList, UA_MonitoredItemAddList)
are consistent with the type of corresponding remote variables in
OPC UA server. Failure to follow these instructions can result in injury or equipment damage. | |
REF_TO ANY
The variables values are given directly through an ANY Type : REF_TO ANY.
REF_TO ANY is a new type defined in Control Expert. It can be used to define a reference on any type of variable. For example, it could be used as type of variable or an element of DDT.
The initialization of the reference (i.e., the variable to which it refers) can be done only via initial value in the data editor.
To simplify the code generation the following syntax is not permitted:
(e.g. VAR_REF : REF_TO ANY) in ST VAR_REF = REF (Var_ANY_TYPE).
A function block considers REF_TO ANY as a buffer of BYTE and knows the size of the buffer in order not to overwrite or over-read the variable.