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AM5726: The PRU of AM5726

lifeng wang
Prodigy 130 points
Part Number: AM5726
Other Parts Discussed in Thread: PROFIBUS,

If the PRU is used as profibus master, how many uart can be used?

I want to establish 4 or 8 profibus bus connections base on 4/8 uart  as profibus master through the PRU, is it possible?

  • 0
    Intellectual 270 points

    Hello,

    I might not be getting your question right, but I will try to answer it anyway.

    On a Profibus network, in general, you will have one Master and as many as 126 slaves (but be aware that if you need more than 31 slaves you will have to use a repeater, so the maximum number of slaves can only be achieved using 4 repeaters, see link below for more details).

    The answer to your question is you only need one UART on your master and another one on each slave. As you can see on the link you need to wire the cables as a bus from the master to each and every slave.

    Maybe, for a very strange reason (or just for fun) what you want to do is have a master and a slave on the same device (board). If I remember correctly (you can check the pinmuxes to be sure) you only need a PRU and the single UART for each master or slave; since you have 10 UARTS on your device but only 2 PRUs I guess you could actually simulate a network with a master and a single slave.

    I hope it helps somewhat.

    Regards.

    Marcos


  • 0 in reply to Marcos Gonzalez1
    Prodigy 130 points

    Hi Marcos

    Thanks for your answers very much!

    There are thousands of profibus slave should be connected to my system, So the more profibus master is the better in my controller.

    Only 2 profibus master can be designed in AM5726 because there are 2 PRUs, isn't it?

    Best Regards.

  • 0 in reply to lifeng wang
    Intellectual 270 points

    Hello,

    Yes, that's it. In general, to have many slaves what you do is add a Master (one for each group of up to 126 slaves; in practice, that number is way lower than that because you have different buses running to different parts of a factory and most branches don't need so many slaves).

    If you use a PLC what you do is add a Master gateway, depending on the vendor and model you might be able to create quite a big network. 

    But if you need thousands of slaves, maybe you should ask yourself why you need to go with Profibus. Profibus sets a very high standard for real-time networking performance, are you sure you need that?

    If you need both real-time performance and many nodes you might need to look at EtherCAT or ProfiNet instead, take a look at the link below, you'll find a nice table comparing different buses and their features. I guess you already know, but TI has a lot of resources for many of those. 

    Regards,

    Marcos

    https://en.wikipedia.org/wiki/Fieldbus

    http://www.ti.com/tool/PRU-ICSS-INDUSTRIAL-SW