I2S Uses CompactRIO to Optimize PLC Automation in Steel Rolling Mills

At Intergrated Industrial Systems (I²S), we have used programmable logic controllers (PLCs) for years to automate our rolling mills. To increase the efficiency and quality of our steel mills, we implemented a gamma gauging system to more accurately control the thickness of metal. Within these systems, we use a gamma ray sensor that requires high-speed, accurate analog I/O along with advanced processing to convert the signal from the sensor to metal thickness. Unfortunately, the PLCs used to automate the rolling mills do not provide the high-speed analog I/O and processing required.

The NI CompactRIO PAC provided the reliability and ruggedness of a PLC for the harsh environment and critical nature of the control system, along with the high-speed analog I/O and signal processing capabilities we required. The analog input modules in CompactRIO connect to gamma-based thickness sensors so we can customize the I/O rates and synchronization with the embedded field-programmable gate array (FPGA) of CompactRIO. The data received from the sensors is then processed in the CompactRIO real-time processor using built-in National Instruments LabVIEW Real-Time function blocks to convert the data from the sensors to an accurate thickness measurement. The data is then transmitted over Ethernet to networked PLCs. With its embedded FPGA and real-time processor, CompactRIO can perform all of the I/O and signal processing and insert a high-accuracy thickness measurement into Ethernet packets without slowing down the PLC control loop.

With NI LabVIEW graphical programming tools, we quickly programmed the FPGA and real-time processor in CompactRIO. Because CompactRIO and our PLCs are Ethernet based, we successfully integrated the CompactRIO PAC with our control systems to optimize our rolling mills with minimal changes to our existing control architecture.