PLC or CompactRIO

[Whooly]

Hi All!

I would like to ask for a little help. I’ve been developing LV RT application with PXI systems for 4 years. Now our company won a bigger assembly line project. The products will moved with a chain conveyor system between the assembly stations and the testbench. Rfid identification will be in each important location for storing state information. The system should communicate with tightening spindles over Profibus. There will be cylinders, optical sensors, 1-2 hundreds digital I/O signal and a testbench with RT PXI system.

What type of control system should we use? This is a typical PLC project but our NI sales manager recommended CompactRIO. I searched for customer’s solutions built with cRIO on the ni.com but i haven’t found similar projects. Mostly cRIO used for high speed daq and control with FPGA. Does cRIO able to deal with a lot of parallel tasks and communicate over Profibus, handle RFID readers? I think FPGA can make programming difficult.

Sorry for bad english

Whooly

[Tim_S]

There's all sorts of questions about sampling rates, update times, etc., but that gets into designing the system. From what you have here I'd put all the I/O on PROFIBUS since you already need it in the system.

Tim

[Christian_L]

Programming LabVIEW RT on cRIO is very similar to PXI when it comes to good design, running multiple processes, memory management, communication, etc. The main difference is that the processor is not as fast.

You are correct that if you need to program the FPGA for your application it will add a little complexity to your development process, specifically learning the differences between programming LV FPGA and LV RT/Windows.

If you are using NI analog and digital modules on cRIO you most likely wouldn't need to program the FPGA and can use the ScanEngine instead. The ScanEngine is a process which runs on the cRIO processor and communicates through the FPGA to I/O modules and provides single point access to I/O channels using I/O variables in LV RT. It is limited to lower acquisition rates (<1 kHz) but that should be adequate for the application you describe.

Does cRIO able to deal with a lot of parallel tasks

You can easily implement parallel tasks, but need to use good design and interprocess communication like you already do in LV RT on PXI.

communicate over Profibus,

NI does not have a Profibus module for cRIO, but there are a couple of alliance partners that offer this product. It does mean that these modules will not be supported in the ScanEngine and you will need to do some programming in LV FPGA to access profibus.

Another option would be to look for a Profibus gateway to serial or Ethernet. I'm not familiar with any specific solutions here and you would need to determine what driver support is available in LV RT on cRIO.

handle RFID readers?

RFID readers would likely interface to cRIO through serial or Ethernet, so again you need to figure out what drivers are available, or if you have the documentation for the communication to the RFID reader you can likely create the serial or Ethernet interface yourself directly in LabVIEW.

[Tim_S]

Another option would be to look for a Profibus gateway to serial or Ethernet.

I wonder if a ethernet/serial to PROFIBUS gateway can act as a master and, if not, what a masterless PROFIBUS network would act like.

RFID readers would likely interface to cRIO through serial or Ethernet, so again you need to figure out what drivers are available, or if you have the documentation for the communication to the RFID reader you can likely create the serial or Ethernet interface yourself directly in LabVIEW.

RFID readers (flipping over the Balluff brochure) are available in serial, DeviceNET, PROFIBUS, PROFINET, Ethernet/IP, CC-Link, IO-Link, etc... Specific units are likely a subset.

Tim

[Whooly]

Now it looks like we will use low cost pxi system. Because the deadline will be close we can't afford to invest to learn new technologies. We will use PXI even if a bit more expensie than plc or cRIO but wi will save money on training, developing time and OPC server.

I searched the internet and i haven't found master PROFIBUS gateway. The Bosch tightening spindle is able to save torque data on an FTP serve so the PXI will read that data file and will control the spindle over I/O signals. The communication with the valve terminals and RFID readers will be over Devicenet.

Thank you for replyes.

Whooly