Hello! What i am about to do is connecting an external SCADA system to a Mitsubishi PLC via OPC server. I have already made some FBs and included their instances in a program in GX Works2, then started a GX Simulator2 and connected it to an OPC Server. From the OPC configurator I have defined some tags with their corresponding device addresses (e.g. D12345). I am using structured variables which device addresses i am entering in the OPC configurator. Tried to make some full rebuild compiling and at first was happy that the devices remain unchanged. The main problem is that after some time this devices change which completely ruined my experiment. Maybe there is some point that I am missing or there is just no way to use a fully functional SCADA connected that way to the Mitsubishi PLC (by OPC)? The question is is there a way to tell a particularly used instance of a function block to have exactly the same device addresses ever.