Is there any standard or good practice that says how often an OPC Client should write data to an OPC Server.

We have a system where the end users OPC Client is only writing data to our OPC Server when the value changes on the client end. This works OK up to a point, as if the OPC Server is rebooted then the OPC client doesn't refresh the OPC Server with data when it connects, only when they need to change it.

I know that an OPC Server will only provide the client with new values of tags being read by the client when it changes when a group is setup with a subscription, but have never heard of anything like this with data being written to an OPC Server.

Thanks in advance for any help received.