Qt QOpcUaNode writeAttribute : error/client Inactivity for Subscription

Question

I have a problem with Qt, I use QOpcUa with open 6254 to read and write tags on a PLC but sometimes the following error occurs: "error / client Inactivity for Subscription" and my program crash. I have identified the problem and this happens because the PLC is writing in this tag at the same time. I would like to know if there is a way to check the availability of the tag before writing?

I have already learned about the subject and there are functions like StatusCode or monitoringStatus but I can't use them properly.

void NodeLoad::writeOrderNumber(QString value)
{
    //if("method that checks the availability of the tag" == true)
        OrderNumber->writeAttribute(QOpcUa::NodeAttribute::Value,value,QOpcUa::Types::String);
    //else qDebug() << "Error";

}

If the tag is not available at the time of writing, the following error occurs: [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 36.

• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 35.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 36.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 35.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 34.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 33.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 32.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 31.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 30.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 29.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 28.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 27.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 26.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 25.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 24.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 23.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 22.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 21.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 20.
• [2019-08-30 09:07:07.019 (UTC+0100)] error/client Inactivity for Subscription 19.
• 09:07:07: The program has unexpectedly finished.
• 09:07:07: The process was ended forcefully.