PLCs receive data from sensors and send commands to actuators. In a large plant, it is likely that there will be several PLCs of different sizes with different capabilities. These are often structured hierarchically, with the highest acting as data concentrators. There aren't many PLCs that act as concentrators in a factory; you can often find them controlling an entire line of production or a specific functional area of the industrial plant. The PLC concentrators meet the needs of the I-IoT data flow very well. They are very powerful and are usually linked to an OPC server gateway provided by the same vendor as the plant or the corporate network, thereby simplifying the task of transferring the data to the cloud over the internet. Sometimes, they are hosted in a separate board on the same rack as an OPC UA server. Since OPC Classic is just run on the Windows box, the same option is not possible for the OPC DA server. If PLC concentrators are not available, we need to connect to the main PLC of every working cell, line production, or plant area from which we need to gather data. In a large plant, we hardly ever just use one PLC concentrator.