ros_opcua_impl_freeopcua

Ths package provides OPC UA client implementation for ROS. The client can connect to an OPC UA server and access simple data from it.

Getting started with ros_opcua_impl_freeopcua

To get start with OPC UA client implementation from this repository first an OPC UA server should be started. For testing one can use example server from freopcua libraray. You can start it using following commands:

roscd && cd ..
./build/ros_opcua_impl_freeopcua/freeopcua/bin/example_server

Then start your client using:

roslaunch ros_opcua_impl_freeopcua client.launch

NOTE: Here is server run on the same computer as the server. If they are running on diffrent computers, instead of localhost insert DNS name or IP address of the computer where server is running. It is also recommended to cross check all values and server using UaExpert OPC UA client.

About examples

If you provide nodeId in service calls the qualifiedName is not required and it can be left out.

Example: Reading and Writing Variables

Use following services to connect to a server, read and write the data:

rosservice call /opcua/opcua_client/connect "endpoint: 'opc.tcp://localhost:4840'"
rosservice call /opcua/opcua_client/read "node:
  nodeId: 'ns=2;i=2001'
  qualifiedName: 'MyVariable'"
rosservice call /opcua/opcua_client/write "node:
  nodeId: 'ns=2;i=2001'
  qualifiedName: 'MyVariable'
data: {type: 'uint32', bool_d: false, int8_d: 0, uint8_d: 0, int16_d: 0, uint16_d: 0, int32_d: 0,
  uint32_d: 100, int64_d: 0, uint64_d: 0, float_d: 0.0, double_d: 0.0, string_d: ''}"

After this lines you should see value changes in OPC UA server of the variable Objects->NewObject->MyVariable to 100. (ATTENTION: you should be fast to check the value, because the example server changes it every few seconds!)

Example: Subscribe to a Variable

rosservice call /opcua/opcua_client/connect "endpoint: 'opc.tcp://localhost:4840'"
rosservice call /opcua/opcua_client/subscribe "node:
  nodeId: 'ns=2;i=2001'
  qualifiedName: 'MyVariable'
callback_topic: 'topic'"

Start echo on created callback topic topic:

rostopic echo /opcuopcua_client/topic

and you should get output after few seconds.

Exmple: Method Call

rosservice call /opcua/opcua_client/call_method "node:
  nodeId: 'ns=2;i=99'
  qualifiedName: 'NewObject'
method:
  nodeId: 'ns=2;i=2003'
  qualifiedName: 'MyMethod'
data:
 - {type: '', bool_d: false, int8_d: 0, uint8_d: 0, int16_d: 0, uint16_d: 0, int32_d: 0,
  uint32_d: 0, int64_d: 0, uint64_d: 0, float_d: 0.0, double_d: 0.0, string_d: ''}"

As result you get “MyMethod called!” output in terminal where example server is started.

Compiling of freeopcua libraray (Not needed - it is done automatically)

This package implements bindings for freeopcua - Open Source C++ OPC-UA Server and Client Library.

First you need to build FreeOpcUa with following commands (asume that you are in FreeOpcUa folder):

mkdir build
cd build
cmake ..
make

And change FreeOpcUa_LIBRARIES variable to be compatible with your environment.

Enjoy!