What's the difference between PLC SCADA & DCS?  A PLC, Programmable Logic Controller, reads inputs, executes logic, and writes to outputs.  A SCADA, Supervisory Control and Data Acquisition connects to a group of PLC's and provides remote monitoring, control, and alarming.  A DCS, distributed control system, has both SCADA and PLC functionality. The PLCs are sometimes called RIO or RTU units often run proprietary or application-specific code, such as a rolling mill DCS.  SCADA can then connect to a DCS using drivers such as Kepware Technologies to integrate the DCS system with other applications across your plant/enterprise.  Hope this answers your question!  

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