NI CompactRIO
CompactRIO (short cRIO ) refers to a family of embedded controllers from National Instruments . The cRIO consists of a controller (with real-time operating system or Windows and an FPGA ) and reconfigurable input and output modules (RIO). In addition, so-called expansion chassis can be connected via Ethernet .
hardware
Each cRIO consists of a controller, a chassis and modules.
Controller
The controller contains a microprocessor and DRAM for executing the software and corresponding flash memory for storing the firmware ( operating system ) and programs. Current controllers also integrate the chassis and the FPGA it contains, some of them using the Zynq chip from Xilinx and this on a chip with an ARM microprocessor.
chassis
The chassis provides space for the modules (so-called C series) and the backplane for connecting the modules to each other and to the controller. In addition, the chassis contains an FPGA , in the current versions Spartan-6 FPGAs from Xilinx with integrated chassis (controller and chassis are one unit) and Virtex-5 FPGAs with separate chassis (controller and chassis can be combined as required). In addition, there are expansion chassis that only have an Ethernet / EtherCAT / MXI connection and an FPGA and can therefore only be used to expand existing controllers, since only the controller can execute the software for operation.
The FPGA is used for high-speed input / output, but can also carry out other high-speed data processing operations (e.g. filtering the input signals or control tasks ) as programmed by the user . The FPGA is connected to the controller via a PCI bus.
For communication with a PC, the controller has an Ethernet connection ( 8P8C ), some models have a second e.g. B. for connecting expansion chassis or EtherCAT expansions such as motor drives. Newer controllers have a VGA connection or DisplayPort connection for displaying information on the operating status or as a replacement for an otherwise necessary PC for the HMI (variants with Windows or real-time Linux and the Xfce interface based on it ), as well as USB Ports for connecting e.g. B. mouse and keyboard or external hard drives.
Modules
While controllers and chassis are only available from National Instruments , there are also third-party plug-in modules for CompactRIO in addition to their C-series modules.
The modules can be hot swapped, so they can be exchanged during operation (provided the software has been programmed accordingly).
software
The real-time operating system VxWorks from Wind River , the Windows operating system from Microsoft or a real-time variant of the Linux operating system (based on Ångström-Linux or OpenEmbedded ) run on the controllers (in the order in which the respective variants appear ).
The LabVIEW graphical development environment is used for programming . The normal version only contains support for the Windows target system. The LabVIEW Real-Time Module is also required for a real-time operating system as the target system. The LabVIEW Real-Time operating system and the driver packages required by some plug-in modules must first be installed on the controller, for example via the network connection with the NI Measurement & Automation Explorer (NI MAX) program, which also enables configuration of the target system.
If you also want to adapt the FPGA, the LabVIEW FPGA Module is also required. This is based on the toolchain from Xilinx (ISE or Vivado) to generate a bit file for the respective FPGA. This is generated from the graphic LabVIEW code via an intermediate stage ( HDL code), but your own modules can also be integrated into the LabVIEW program using VHDL . A prefabricated bit file is loaded onto the FPGA without adaptation (the so-called scan interface), which reads the data from the modules cyclically and makes it available for real-time use, as the modules are only accessible via the FPGA.
Applications
CompactRIOs are mostly used in the field of control and automation when compactness ( small form factor ) and robustness (−40 ° C to +70 ° C in operation with passive cooling, vibration and shock resistance) are required. They can be used independently (control by FPGA and real-time program) or with HMI or PC connection for monitoring ( SCADA ) or tests in the high-speed range. In these areas they can replace a PLC .
For pure (PC-supported) data acquisition, National Instruments offers CompactDAQ, a simpler version (without FPGA and real-time) that is also easier to program. The CompactRIO bus is also not designed for high data rates (GB / s), so the modules have corresponding sampling rates in the range of a few 10 to 100 kS / s. Similar requirements for higher data rates are met by a PXI system that is designed around a PXI or PXI Express bus and enables data rates of up to 6 GB / s in each direction via the bus.
Individual evidence
- ↑ http://sine.ni.com/nips/cds/view/p/lang/de/nid/14155
- ↑ http://sine.ni.com/nips/cds/view/p/lang/de/nid/210398
- ↑ http://sine.ni.com/nips/cds/view/p/lang/de/nid/208478
- ↑ ftp://ftp.ni.com/pub/branches/germany/2013/artikel/12-december/06_joerg_hessdoerfer_neue_real-time-perspektiven_fuer_die_embedded-welt_elektronik_informationen.pdf