WagoOpcUaVisu

Trying to control my Wago PFC100 with a web application which connects to the PLC via OPC UA. This is a hobby project of mine and a work in progress.

First step: Test out OPC UA connection

Steps in eCockpit!:

• Assuming you have a running program on it which compiles and has some variables in it.

• Disconnect from the running PLC

• Right click on Application (PFC100)

• Click on Symbol Configuration

• Select "Support OPC UA Features"

• In the tab "Symbol Configuration" choose some IOs you want to manipulate via OPC UA

• Install this via pip install opcua

• Get the IP address of your PLC

• Test if you can connect to your PLC via OPC UA with this script (slightly modified version of this)

  import sys
  sys.path.insert(0, "..")
  
  
  from opcua import Client
  
  
  if __name__ == "__main__":
  
  client = Client("opc.tcp://192.168.99.99:4840/")
  # client = Client("opc.tcp://admin@localhost:4840/freeopcua/server/") #connect using a user
  try:
      client.connect()
  
      # Client has a few methods to get proxy to UA nodes that should always be in address space such as Root or Objects
      root = client.get_root_node()
      print("Objects node is: ", root)
  
      # Node objects have methods to read and write node attributes as well as browse or populate address space
      print("Children of root are: ", root.get_children())
  
  
  finally:
      client.disconnect()

• Now you should see something like this Children of root are: [Node(TwoByteNodeId(i=87)), Node(TwoByteNodeId(i=86)), Node(TwoByteNodeId(i=85))] as output

• This is very cryptic and you don´t know which node is which

• To solve this, download the program UAExpert from Unified Automation

• Now connect to your OPC UA server with the same IP + port combination you used in the python example

• On the left hand side of the program in the Address Space window, select the address space including the word CODESYSSPV3...

• Go down the tree: Root/Objects/DeviceSet/WAGO 750-8100.../Resources/Application/GlobalVars/IoConfig_Globals_Mapping

• Here you should see the formerly in eCockpit! selected IOs

• Select a IO and look to the attributes window on the top right

• The first point shows the NodeID (something like ns=1;s=abc)

• Add some lines to your python code

  myIO = client.get_node("ns=1;s=abc")
  print(myIO.get_value())

• Now the current value of the IO should be printed to the console

• Make sure that the IO you have chosen has read and write permission (you can see this in the Symbol Configuration when you look at the little arrow symbol, this should be a bidirectional arrow)

• Now you can write to your IO

  myIO.set_value(True) # if it is of type boolean
  

More coming soon