Hello and I will explain how to create a OPCUA Client in RoboDK and communicate with TwinCAT OPCUA Server. The Robot will start a different program – depending on your command.Let’s create a station with 1 robot and 2 robot programs first.

RoboDK Side

Program1

This is program1.

Program2

This is program2.

Python Script

Click the python icon to create a python script .

Right click the script and press Edit Python script.

Code

We will use this library.

pip install opcua

https://github.com/FreeOpcUa/python-opcua

from opcua import Client,ua
from robodk import robolink # RoboDK API
from robodk import robomath # Robot toolbox
RDK = robolink.Robolink()

def SetNodeValue(Node,value):
DataType=Node.get_data_type_as_variant_type()
DataValue=ua.DataValue(ua.Variant(value,DataType))
Node.set_data_value(DataValue)

item = RDK.Item(‘UR3’)
if item.Valid():
print(‘Robot is found..’)

Programs=[‘Coke’,’Beer’]

ENDPOINT=’opc.tcp://127.0.0.1:4840′
REGSNODE=’ns=4;s=GVL.Reg’
BUSYNODE=’ns=4;s=GVL.bBusy’
ENDNODE=’ns=4;s=GVL.bEnd’

GetProgram=False

client=Client(ENDPOINT)
client.connect()
Regs=client.get_node(REGSNODE)
Busy=client.get_node(BUSYNODE)
End=client.get_node(ENDNODE)
_busy=False
SetNodeValue(Busy,False)
while True:
cmd=Regs.get_value()[0]
if cmd is 0:
GetProgram=False
_busy=False
SetNodeValue(Busy,False)
SetNodeValue(End,False)
_busy=False

if cmd >0 :
if not GetProgram and not _busy :
prog=RDK.Item(Programs[cmd-1])
print(prog.Name())
GetProgram=True
if not _busy:
value = prog.RunProgram()
SetNodeValue(Busy,True)
SetNodeValue(End,False)
_busy=True
if not prog.Busy() :
SetNodeValue(Busy,False)
SetNodeValue(End,True)
GetProgram=False

TwinCAT Side

Here is the flow between RoboDK and TwinCAT.

The Operator can start a different program from the screen, and then TwinCAT will send a start command to RoboDK.

RoboDK will check the actual value of the command, if the value is greater than 0, python script will get the RoboDK robot program object and start it, otherwise rest all the Flags.

The Busy flag will remain at 1 until the program is completed. FInally, A End Flag will be sent from RoboDK to TwinCAT, TwinCAT will reset the command.

Then RoboDK will reset all the flags.

GVL

OPCUA NodeのGVLです。

{attribute ‘qualified_only’}
VAR_GLOBAL
{attribute ‘OPC.UA.DA’ := ‘1’}
Reg:ARRAY[0..99]OF INT;
{attribute ‘OPC.UA.DA’ := ‘1’}
bBusy:BOOL;
{attribute ‘OPC.UA.DA’ := ‘1’}
bEnd:BOOL;

END_VAR

MAIN

These are the nodes of OPCUA Server.

VAR

PROGRAM MAIN
VAR
bBeer:BOOL;
bCoke:BOOL;
p1:R_TRIG;
END_VAR

Program

IF bBeer THEN
bBeer:=FALSE;
GVL.Reg[0]:=1;
END_IF

IF bCoke THEN
bCoke:=FALSE;
GVL.Reg[0]:=2;
END_IF

p1(clK:=GVL.bEnd);

IF p1.Q THEN
GVL.Reg[0]:=0;
END_IF