open62541 (http://open62541.org) is an open source and free implementation of OPC UA (OPC Unified Architecture) written in the common subset of the C99 and C++98 languages. The library is usable with all major compilers and provides the necessary tools to implement dedicated OPC UA clients and servers, or to integrate OPC UA-based communication into existing applications. open62541 library is platform independent. All platform-specific functionality is implemented via exchangeable plugins. Plugin implementations are provided for the major operating systems.
open62541 is licensed under the Mozilla Public License v2.0. So the open62541 library can be used in projects that are not open source. Only changes to the open62541 library itself need to published under the same license. The plugins, as well as the server and client examples are in the public domain (CC0 license). They can be reused under any license and changes do not have to be published.
The library is available in standard source and binary form. In addition, the single-file source distribution merges the entire library into a single .c and .h file that can be easily added to existing projects. Example server and client implementations can be found in the /examples directory or further down on this page.
Build Status:
Code Quality:
General Project Info:
open62541 implements the OPC UA binary protocol stack as well as a client and server SDK. The final server binaries can be well under 100kb, depending on the selected features and the size of the information model.
open62541 is currently self-certifying. That is, the Conformance Testing Tools (CTT) of the OPC Foundation are regularly applied. But the SDK has not started an official certification so far. The CTT configuration and results are tracked at https://github.com/open62541/open62541-ctt. The OPC UA profiles under regular test in the CTT are currently:
The goal for the upcoming 0.4 release is to support the Embedded UA Server profile in the CTT. See the page on open62541 Features for an in-depth look at the support for the conformance units that make up the OPC UA profiles.
On most systems, open62541 requires the C standard library only. For dependencies during the build process, see the following list and the build documentation for details.
We emphasize code quality. The following quality metrics are continuously checked and are ensured to hold before an official release is made:
A general introduction to OPC UA and the open62541 documentation can be found at http://open62541.org/doc/current. Past releases of the library can be downloaded at https://github.com/open62541/open62541/releases. To use the latest improvements, download a nightly build of the single-file distribution (the entire library merged into a single source and header file) from http://open62541.org/releases. Nightly builds of MSVC binaries of the library are available here.
For individual discussion and support, use the following channels:
We want to foster an open and welcoming community. Please take our code of conduct into regard.
Jointly with the overall open62541 community, the core maintainers steer the long-term development. The current core maintainers are (as of April 2018, in alphabetical order):
The open62541 community handles support requests for the open source library and its development. Custom development and individual support is provided by commercial partners that are affiliated with open62541:
For custom development that shall eventually become part of the open62541 library, please keep one of the core maintainers in the loop. Again, please note that all changes to files that are already licensed under the MPLv2 automatically become MPLv2 as well. Static linking of the open62541 library with code under a different license is possible. All architecture-specific code is implemented in the form of exchangeable plugins under a very permissible CC0 license.
As an open source project, new contributors are encouraged to help improve open62541. The following are good starting points for new contributors:
A list of projects and companies using our open62541 stack can be found in our Wiki:
https://github.com/open62541/open62541/wiki/References-to-open62541
For every release, we provide some pre-packed release packages which you can directly use in your compile infrastructure.
Have a look at the release page and the corresponding attached assets.
A more detailed explanation on how to install the open62541 SDK is given in our documentation.
You can not directly download a .zip package from the main branches using the Github UI, since then some of the submodules and version strings are missing. Therefore you have three options to install and use this stack:
Recommended: Use any of the prepared packages attached to every release or in the package repository of your distro (if available).
Please check the install guide for more info.
Download a .zip package of special pack/ branches.
These pack branches are up-to-date with the corresponding base branches, but already have the submodules in-place and the version string set correctly.
Here are some direct download links for the current pack branches:
Clone this repository and initialize all the submodules using git submodule update --init --recursive. Then either use make install or setup your CMake project correspondingly.
A complete list of examples can be found in the examples directory.
To build the examples, we recommend to install the open62541 project as mentioned in previous section.
The following simple server example can be built using gcc, after you installed open62541 on your system.
Using the GCC compiler, just run gcc -std=c99 -lopen62541 -DUA_ARCHITECTURE_POSIX <server.c> -o server (under Windows you may need to add -lws2_32 and change -DUA_ARCHITECTURE_POSIX to -DUA_ARCHITECTURE_WIN32).
#include <signal.h> #include <open62541/server.h> #include <open62541/server_config_default.h> UA_Boolean running = true; void signalHandler(int sig) { running = false; } int main(int argc, char** argv) { signal(SIGINT, signalHandler); /* catch ctrl-c */ /* Create a server listening on port 4840 */ UA_Server *server = UA_Server_new(); UA_ServerConfig_setDefault(UA_Server_getConfig(server)); /* Add a variable node */ /* 1) Define the node attributes */ UA_VariableAttributes attr = UA_VariableAttributes_default; attr.displayName = UA_LOCALIZEDTEXT("en-US", "the answer"); UA_Int32 myInteger = 42; UA_Variant_setScalar(&attr.value, &myInteger, &UA_TYPES[UA_TYPES_INT32]); /* 2) Define where the node shall be added with which browsename */ UA_NodeId newNodeId = UA_NODEID_STRING(1, "the.answer"); UA_NodeId parentNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER); UA_NodeId parentReferenceNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_ORGANIZES); UA_NodeId variableType = UA_NODEID_NULL; /* take the default variable type */ UA_QualifiedName browseName = UA_QUALIFIEDNAME(1, "the answer"); /* 3) Add the node */ UA_Server_addVariableNode(server, newNodeId, parentNodeId, parentReferenceNodeId, browseName, variableType, attr, NULL, NULL); /* Run the server loop */ UA_StatusCode status = UA_Server_run(server, &running); UA_Server_delete(server); return status; }
#include <stdio.h> #include <open62541/client.h> #include <open62541/client_config_default.h> int main(int argc, char *argv[]) { /* Create a client and connect */ UA_Client *client = UA_Client_new(); UA_ClientConfig_setDefault(UA_Client_getConfig(client)); UA_StatusCode status = UA_Client_connect(client, "opc.tcp://localhost:4840"); if(status != UA_STATUSCODE_GOOD) { UA_Client_delete(client); return status; } /* Read the value attribute of the node. UA_Client_readValueAttribute is a * wrapper for the raw read service available as UA_Client_Service_read. */ UA_Variant value; /* Variants can hold scalar values and arrays of any type */ UA_Variant_init(&value); status = UA_Client_readValueAttribute(client, UA_NODEID_STRING(1, "the.answer"), &value); if(status == UA_STATUSCODE_GOOD && UA_Variant_hasScalarType(&value, &UA_TYPES[UA_TYPES_INT32])) { printf("the value is: %i\n", *(UA_Int32*)value.data); } /* Clean up */ UA_Variant_deleteMembers(&value); UA_Client_delete(client); /* Disconnects the client internally */ return status; }
