Hello！Help!

I'm trying to connect to a sinumerik 828d with OPC UA to monitor its status.

But after I poll reading some NC values like "/Bag/State/opMode"  for several hours i will get  status code  "BadAttributeIdInvalid".And after this, i will lost the connection with the machine And cannot connect  it again  before restart it (sinumerik 828d ).

Is there anyone had met this problem and knows the solution.

Thanks for your reading and hope your help.

Do you get any error messages? Does the network work? Maybe set a ping with the -t option and have a look when the next error appears whether ping is getting worse or the connection gets lost.

Yes，I am sure  the network works .And i get a status code "BadAttributeIdInvalid" when reading . 

And i found i can reconnect to the opc server on 828d after items return "BadAttributeIdInvalid" status code.But when i try to read the same item it return "BadAttributeIdInvalid" status code before i restart the machine.

In my client program i was using readValue() method  but not subscription .Now i change my program to subscription ,and it had worked for 3days without any error.So i think the readValue() method has something wrong,or i don‘t used it in a right way.

In my case was same as you?

I wondering actually your NC connection is OK? My case after 2weeks, same problem happened.