OPC-UA Commands

Generic Command Access

The command module of OPC-UA server can be accessed using the command info structure.

The command address is made of two node ids. The "@"-sign separates the two ids.
Example: {<object_id>}"@"{<command_id}

Example:

{
  "Id": "D2DFA580-E5C6-4E49-A845-2C9C902899F7",
  "Name": "ReadValue",
  "Type": "CommandNode",
  "Address": "{ns=2;g={ECE37FDF-4862-4543-AF23-48FFDB8203C7}}@{ns=2;g={0012A45C-E9FD-471E-8AD3-8BB85A33B186}}",
  "Arguments": [
    {
      "Name": "Address",
      "DataType": "System.String",
      "Type": "Input"
    },
    {
      "Name": "Value",
      "DataType": "System.String",
      "Type": "Output"
    }
  ]
}

Special Command Access

The OPC-UA control provides following special commands:

• opc:WriteData: Writes data to an OPC-UA data node
• opc:ReadData: Reads data from an OPC-UA data node

WriteData

opc:WriteData uses following arguments:

Name	Description	Data Type
Address	Address to write data to a data node	System.String
DataType	Data type of the OPC-UA data node	System.String
Value	Value to write	System.String

Example:

{
  "Id": "{30A53102-6737-4A3E-9514-047B938F78A6}",
  "Name": "WriteData",
  "Type": "CommandNode",
  "Address": "opc:WriteData",
  "Arguments": [
    {
      "Name": "Address",
      "DataType": "System.String",
      "Type": "Input"
    },
    {
      "Name": "DataType",
      "DataType": "System.String",
      "Type": "Input"
    },
    {
      "Name": "Value",
      "DataType": "System.String",
      "Type": "Input"
    }
  ]
}

ReadData

opc:ReadData uses following arguments:

Name	Description	Data Type
Address	Address to write data to a data node	System.String

Output argument is:

Name	Description	Data Type
Value	Value from the DataNode	System.String

Example:

{
  "Id": "{48060B81-17B8-477C-9CC9-1B0858465780}",
  "Name": "ReadData",
  "Type": "CommandNode",
  "Address": "opc:ReadData",
  "Arguments": [
    {
      "Name": "Address",
      "DataType": "System.String",
      "Type": "Input"
    },
    {
      "Name": "Value",
      "DataType": "System.String",
      "Type": "Output"
    }
  ]
}