open62541 (http://open62541.org) is an open source and free implementation of OPC UA (OPC Unified Architecture). open62541 is a C-based library that contains all the necessary tools to set up a dedicated OPC UA server or to integrate OPC UA-based communication into existing applications (linking with C++ projects is possible). An example server implementation can be found in the /examples directory or further down on this page.
open62541 is licensed under the LGPL + static linking exception. That means open62541 can be freely used also in commercial projects, although changes to the open62541 library itself need to be released under the same license. The server and client implementations in the /examples directory are in the public domain (CC0 license). They can be used under any license and changes don't have to be published.
A general introduction to OPC UA and the open62541 documentation can be found at http://open62541.org/doc. Build instruction are here: https://github.com/acplt/open62541/wiki/Building-open62541.
For discussion and help, you can use
- the mailing list
- our IRC channel
- the bugtracker
As an open source project, we invite new contributors to help improving open62541. If you are a developer, your bugfixes and new features are very welcome. Note that there are ways to contribute even without deep knowledge of the project or the UA standard:
- Report bugs
- Improve the documentation
- Work on issues marked as "easy hacks"
#include <signal.h>
/* provided by the open62541 lib */
#include "ua_server.h"
/* provided by the user, implementations available in the /examples folder */
#include "logger_stdout.h"
#include "networklayer_tcp.h"
#define WORKER_THREADS 2 /* if multithreading is enabled */
#define PORT 16664
UA_Boolean running = UA_TRUE;
void signalHandler(int sign) {
running = UA_FALSE;
}
int main(int argc, char** argv) {
/* catch ctrl-c */
signal(SIGINT, signalHandler);
/* init the server */
UA_Server *server = UA_Server_new();
NetworklayerTCP *nl = ServerNetworkLayerTCP_new(UA_ConnectionConfig_standard, PORT);
UA_Server_addNetworkLayer(server, nl);
/* add a variable node */
UA_Variant *myIntegerVariant = UA_Variant_new();
UA_Int32 myInteger = 42;
UA_Variant_setScalarCopy(myIntegerVariant, &myInteger, &UA_TYPES[UA_TYPES_INT32]);
UA_QualifiedName myIntegerName;
UA_QUALIFIEDNAME_ASSIGN(myIntegerName, "the answer");
UA_NodeId myIntegerNodeId = UA_NODEID_NULL; /* assign a random free nodeid */
UA_NodeId parentNodeId = UA_NODEID_STATIC(0, UA_NS0ID_OBJECTSFOLDER);
UA_NodeId parentReferenceNodeId = UA_NODEID_STATIC(0, UA_NS0ID_ORGANIZES);
UA_Server_addVariableNode(server, myIntegerVariant, myIntegerName,
myIntegerNodeId, parentNodeId, parentReferenceNodeId);
/* run the server loop */
UA_StatusCode retval = UA_Server_run(server, WORKER_THREADS, &running);
UA_Server_delete(server);
return retval;
}