OPCUADSOutput

Warning

The OPCUADataSource is only available in distributions where open62541 is installed.

The OPCUADSOutput DataSource can be used to stream application data over the OPC UA protocol. This allows interfacing the application with any OPC UA-based monitoring or control applications.

Warning

This DataSource writes to OPCUA synchronously on the same thread as the MARTe RealTimeThread, which may negatively impact the real-time performance of the application. Decoupling mechanisms are discussed later in the tutorial (see the sections on RealTimeThreadAsyncBridge and RealTimeThreadSynchronisation).

The DataSource only supports structured types as defined in Structured types.

Given that the OPCUA server ports need to be unique in order to avoid port clashes, the configuration file ../Configurations/MassSpring/RTApp-MassSpring-40.cfg will be automatically updated from a Makefile.cfg.

The OPCUA types are hosted using a MARTe2 OPCUAServer, which in this example is instantiated in the same configuration file as the application.

The objective of this example is to monitor the application data using OPCUA.

OPCUAServer configuration. Note that the OPCUA server port is automatically replaced by the Makefile.cfg.
 1+OPCUAServer = {
 2    Class = OPCUA::OPCUAServer
 3    StackSize = 1048576 
 4    CPUs = 0x1
 5    Run = 1 
 6    Authentication = None
 7    Port = OPCUA_PORT
 8    AddressSpace = {
 9        MassSpringDemo = {
10            Type = MonitorControl 
11            NumberOfElements = 1
12        }
13    }
14}
15$MassSpringApp = {
16    Class = RealTimeApplication
IOGAM to copy from the flattened signal type definition into a structured type. Note that the OPCUADSOutput requires a Trigger signal, which in this case is the Time signal.
 1        +GAMWriter = {
 2            Class = IOGAM
 3            InputSignals = {
 4                Time = {
 5                    DataSource = DDB1
 6                    Type = uint32
 7                }
 8                ReferencePosition = {
 9                    DataSource = DDB1
10                    Type = float64
11                    DataSource = OPCUAWriter
12                    Type = MonitorControl
13                    Trigger = 1
14                    TriggerSignal = "Monitor.Time"
15                }
16            }
17        }
OPCUADSOutput DataSource configuration. Note that the OPCUA address is automatically replaced by the Makefile.cfg.
 1        +OPCUAWriter = {
 2            Class = OPCUADataSource::OPCUADSOutput
 3            Address = OPCUA_FULL_URL
 4            Authentication = None
 5            Signals = {
 6                Monitor = {
 7                    NamespaceIndex = 1
 8                    Type = MonitorControl 
 9                    Path = "MassSpringDemo"
10                }
11            }
12        }

Running the application

Start the application with:

make -C ../Configurations/MassSpring/ -f Makefile.cfg
./MARTeApp.sh -f ../Configurations/MassSpring/RTApp-MassSpring-40_Gen.cfg -l RealTimeLoader -s State1

Once the application is running, inspect the screen output and verify that the application is running without any issues. The log should show entries similar to the following:

...
$ [Warning - Threads.cpp:181]: Failed to change the thread priority (likely due to insufficient permissions)
$ [Information - RealTimeLoader.cpp:111]: Started application in state State1
$ [Information - MARTeApp.cpp:135]: Application starting
$ [Information - LoggerBroker.cpp:152]: Time [0:0]: 0
$ [Information - LoggerBroker.cpp:152]: Time [0:0]:1000000
...

Open another terminal and check that the OPCUA records are being updated with the application data by running another MARTe2 application.

./MARTeApp.sh -f ../Configurations/MassSpring/RTApp-MassSpring-40-Monitor_Gen.cfg -l RealTimeLoader -s State1

The output should be similar to the following:

$ [Information - LoggerBroker.cpp:152]: Monitor.Time [0:0]:115290000
$ [Information - LoggerBroker.cpp:152]: Monitor.Control.ReferencePosition [0:0]:1.972000
$ [Information - LoggerBroker.cpp:152]: Monitor.Control.Position [0:0]:1.916281
$ [Information - LoggerBroker.cpp:152]: Monitor.Control.PositionDisturbed [0:0]:1.911329
$ [Information - LoggerBroker.cpp:152]: Monitor.Control.PositionFiltered [0:0]:1.917298
$ [Information - LoggerBroker.cpp:152]: Monitor.Control.PositionM [0:0]:1.923568
$ [Information - LoggerBroker.cpp:152]: Monitor.Control.Velocity [0:0]:-0.125965
$ [Information - LoggerBroker.cpp:152]: Monitor.Control.VelocityM [0:0]:-0.194689
$ [Information - LoggerBroker.cpp:152]: Monitor.Control.PositionErr [0:0]:-0.054702
$ [Information - LoggerBroker.cpp:152]: Monitor.Control.Force [0:0]:13.292912
$ [Information - LoggerBroker.cpp:152]: Monitor.Control.ForceAverage [0:0]:15.260224
$ [Information - LoggerBroker.cpp:152]: Monitor.Control.ForceStdDev [0:0]:2.372243
$ [Information - LoggerBroker.cpp:152]: Monitor.Control.ForceMax [0:0]:19.272639
$ [Information - LoggerBroker.cpp:152]: Monitor.Control.ForceMin [0:0]:9.151042

Note

You can also use any OPCUA client to connect to the MARTe2 OPCUA server and monitor the application data.

For example, if the Python opcua library is installed on your system, you can use the Python script located in ../Test/Integrated/opcua_monitor.py to connect to the server and print the values of the nodes being written by the application.

OPCUA_PORT=`awk '/\+OPCUAServer/,/}/ {if ($1=="Port") print $3}' ../Configurations/MassSpring/RTApp-MassSpring-40_Gen.cfg`;echo "OPCUA_PORT=$OPCUA_PORT"
python3.6 ../Test/Integrated/opcua_monitor.py -p $OPCUA_PORT -s MassSpringDemo

As explained in the OPCUADSOutput documentation, it is possible to associate a timestamp signal with one or more output signals. When a timestamp signal is configured, its value is used to populate the OPCUA SourceTimestamp field when writing the associated nodes.

Exercises

Ex. 1: Statistics monitoring

Monitor the statistics signals as part of another OPCUA structure.

  1. Edit the file ../Configurations/MassSpring/RTApp-MassSpring-41.cfg and add a new DataSource instance to write the signal MonitorPerf from the GAMWriterPerf IOGAM.

Important

The OPCUADSOutput does not allow writing multiple structured signals, so a new DataSource needs to be added to the configuration file.

  1. Start the sender application.

make -C ../Configurations/MassSpring/ -f Makefile.cfg
./MARTeApp.sh -f ../Configurations/MassSpring/RTApp-MassSpring-41_Gen.cfg -l RealTimeLoader -s State1

  1. Open another terminal and check that the OPCUA records are being updated with the application data by running another MARTe2 application.

./MARTeApp.sh -f ../Configurations/MassSpring/RTApp-MassSpring-41-Monitor_Gen.cfg -l RealTimeLoader -s State1
Solution

The solution is to add a new OPCUADSOutput instance.

New OPCUADSOutput DataSource configuration.
 1        +OPCUAWriterPerf = {
 2            Class = OPCUADataSource::OPCUADSOutput
 3            Address = OPCUA_FULL_URL
 4            Authentication = None
 5            Signals = {
 6                MonitorPerf = {
 7                    NamespaceIndex = 1
 8                    Type = MonitorPerformance
 9                    Path = "MassSpringDemoPerformance"
10                }
11            }
12        }

The outputs from the monitor application (running on the other terminal) should be similar to the following:

$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMHist.ReadTime [0:0]:9848
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMHist.ExecTime [0:0]:9849
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMHist.WriteTime [0:0]:9849
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMMathExpr.ReadTime [0:0]:9849
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMMathExpr.ExecTime [0:0]:9849
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMMathExpr.WriteTime [0:0]:9849
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMConversion.ReadTime [0:0]:9849
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMConversion.ExecTime [0:0]:9849
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMConversion.WriteTime [0:0]:9849
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMFilterMovingAvg.ReadTime [0:0]:9849
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMFilterMovingAvg.ExecTime [0:0]:9849
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMFilterMovingAvg.WriteTime [0:0]:9850
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMMathTrigger.ReadTime [0:0]:9850
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMMathTrigger.ExecTime [0:0]:9850
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMMathTrigger.WriteTime [0:0]:9850
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMMathTriggerSecond.ReadTime [0:0]:9850
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMMathTriggerSecond.ExecTime [0:0]:9850
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMMathTriggerSecond.WriteTime [0:0]:9850
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMDisplay.ReadTime [0:0]:9850
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMDisplay.ExecTime [0:0]:9850
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMDisplay.WriteTime [0:0]:9850
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMWriter.ReadTime [0:0]:9851
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMWriter.ExecTime [0:0]:9851
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.GAMWriter.WriteTime [0:0]:9896
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.Thread1.CycleTime [0:0]:10001
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.Thread1.CycleTimeAverage [0:0]:9998
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.Thread1.CycleTimeMovingAverage [0:0]:9998.599052
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.Thread1.CycleTimeStdDev [0:0]:141
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.Thread1.CycleTimeMax [0:0]:10076
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.Thread1.CycleTimeMin [0:0]:9918
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.Thread1.CycleTimeHistogram [0:10]:{ 2 1 0 0 0 137 0 0 1 2 1 }
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.Thread1.FreeTimeHistogram [0:10]:{ 0 0 1 0 0 1 0 1 0 29 112 }
$ [Information - LoggerBroker.cpp:152]: MonitorPerf.Perf.Thread1.GAMsExecutionTime [0:0]:58

Ex. 2: Timestamping

The objective of this exercise is to use another signal to timestamp OPCUA against a given signal instead of the timestamp that is automatically set by the library.

  1. Edit the file ../Configurations/MassSpring/RTApp-MassSpring-42.cfg and add a new signal named AbsoluteTimeStamp to the OPCUAWriter DataSource.

  2. Make sure that the signal contains the property DefaultTimestampSignal set to 1.

  3. Modify the IOGAM GAMWriter to copy the AbsoluteTimeStamp signal from the DDB1 into the new signal in the OPCUAWriter DataSource.

Note

As explained in the LinuxTimer documentation, the AbsoluteTimeStamp signal is the counter multiplied by the period (counting from the Epoch). If you are running on a CODAC Core System, you may use the TcnTimeProvider to obtain the absolute time.

  1. Start the sender application.

make -C ../Configurations/MassSpring/ -f Makefile.cfg
./MARTeApp.sh -f ../Configurations/MassSpring/RTApp-MassSpring-42_Gen.cfg -l RealTimeLoader -s State1

  1. Open another terminal and check that the OPCUA records are being updated with the application data by running the following Python application (assuming that the Python opcua library is installed on your system):

OPCUA_PORT=`awk '/\+OPCUAServer/,/}/ {if ($1=="Port") print $3}' ../Configurations/MassSpring/RTApp-MassSpring-42_Gen.cfg`;echo "OPCUA_PORT=$OPCUA_PORT"
python3.6 ../Test/Integrated/opcua_monitor.py -p $OPCUA_PORT -s MassSpringDemo --print_time_stamps
Solution

The solution is to add the AbsoluteTime to the DataSource and set the DefaultTimestampSignal property.

New OPCUADSOutput DataSource configuration.
 1        +OPCUAWriter = {
 2            Class = OPCUADataSource::OPCUADSOutput
 3            Address = OPCUA_FULL_URL
 4            Authentication = None
 5            Signals = {
 6                AbsoluteTime = {
 7                    Type = uint64 
 8                    DefaultTimestampSignal = 1
 9                }
10                Monitor = {
11                    NamespaceIndex = 1
12                    Type = MonitorControl 
13                    Path = "MassSpringDemo"
14                }
15            }
16        }

The outputs from the monitor application (running on the other terminal) should be similar to the following (note that the timestamps are near the Epoch):

- MassSpringDemo
- Time:22100000 | src_ts:1970-01-01 01:51:12.614091 | srv_ts:None
- Control
    - ReferencePosition:0.8280000000000002 | src_ts:1970-01-01 01:51:12.614101 | srv_ts:None
    - Position:0.7308889950318065 | src_ts:1970-01-01 01:51:12.614101 | srv_ts:None
    - PositionDisturbed:0.7329734151785503 | src_ts:1970-01-01 01:51:12.614101 | srv_ts:None
    - PositionFiltered:0.726084634618206 | src_ts:1970-01-01 01:51:12.614101 | srv_ts:None
    - PositionM:0.7292609341046103 | src_ts:1970-01-01 01:51:12.614101 | srv_ts:None
    - Velocity:0.3796677587971925 | src_ts:1970-01-01 01:51:12.614101 | srv_ts:None
    - VelocityM:0.3941233025599467 | src_ts:1970-01-01 01:51:12.614111 | srv_ts:None
    - PositionErr:-0.10212367380322629 | src_ts:1970-01-01 01:51:12.614111 | srv_ts:None
    - Force:7.6191469671596765 | src_ts:1970-01-01 01:51:12.614111 | srv_ts:None
    - ForceAverage:4.3079819265028485 | src_ts:1970-01-01 01:51:12.614111 | srv_ts:None
    - ForceStdDev:1.8327930024983468 | src_ts:1970-01-01 01:51:12.614111 | srv_ts:None
    - ForceMax:7.6191469671596765 | src_ts:1970-01-01 01:51:12.614111 | srv_ts:None
    - ForceMin:1.325131643231978 | src_ts:1970-01-01 01:51:12.614121 | srv_ts:None