|
|
@@ -11,12 +11,12 @@ late, OPC UA is marketed as the one standard for non-realtime industrial communi
|
|
|
|
|
|
We believe that it is best to understand OPC UA <em>from the inside out</em>, building upon conceptually
|
|
|
simple first principles. After establishing a first understanding, we go on explaining how these
|
|
|
-principles are realized in detail. Examples are given based on the </em>open62541</em> implementation of the
|
|
|
+principles are realized in detail. Examples are given based on the <em>open62541</em> implementation of the
|
|
|
standard.
|
|
|
|
|
|
<h2>OPC UA, a collection of services</h2>
|
|
|
|
|
|
-In OPC-UA, all communication is based on service calls, each consisting of a request and a response
|
|
|
+In OPC UA, all communication is based on service calls, each consisting of a request and a response
|
|
|
message. Be careful to note the difference between services and methods. Services are pre-defined in
|
|
|
the standard and cannot be changed. But you can use the <em>Call</em> service to invoke user-defined
|
|
|
methods on the server.
|
|
|
@@ -96,7 +96,7 @@ open62541, these are defined in ua_types.h.
|
|
|
<tr> <td>UInt64</td> <td>ExpandedNodeId</td> <td> </td> </tr>
|
|
|
</table>
|
|
|
|
|
|
-The builtin datatypes are combined to more complex structures. When the structure contains an array,
|
|
|
+The builtin datatypes are combined into more complex structures. When the structure contains an array,
|
|
|
then the size of the array is stored in an Int32 value just before the array itself. A size of -1
|
|
|
indicates an undefined array. Positive sizes (and zero) have the usual semantics.
|
|
|
|
Markus Graube