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Overview and Strategy
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Introduction
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The Control Systems of ITER are divided into three main categories:

- PLCs: Slow processing (latency between 10 ms and 100 ms) and multiple+local I/O
- Fast Controllers (PC): High processing capabilities, high bandwidth, medium latency (between 100 us and 10 ms) and local I/O  

The HotRIO Control Systems are meant to provide solutions where lower latency (between 10 us and sub-us) and high bandwith (up to 1 Gbps) are required and also, where a high number of distributed or local IOs (hundreds) are needed. 

The main features of a HotRIO Control system are: 

- FPGA processors boards with adaptable processing capabilities: Medium (Lattice FPGA) or Large (Xilinx FPGA)
- Low latency and high bandwidth communications with timing capabilities through specific protocol based on fiber 1GbE physical layer (:ref:`HotRIO Protocol`)
- Distributed, Remote and Local IO Capabilities: ADCs, DACs, DIO (fiber and copper)
- Modular and Flexible:

     * Several expansion IO boards connected to the same FPGA through the backplane
     * Several FPGA boards connected in daisy chain through fiber