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Which evaluation board for AM335x for using Modbus RTU?

Jeff Stringer
Intellectual 320 points
Other Parts Discussed in Thread: AM3352, PROFIBUS, AM3356, AM3359

I have an industrial application that I would like to prototype with the Sitara family and so I'm looking for a eval board.  Seems like there are lots to choose from (beagle, various TI eval boards).  Here are the features I'd like:

1) RS-485 for Modbus RTU ,  2) SPI port for connecting to some other hardware, 3) USB port for interfacing to a PC application, 4) RJ45 for ethernet port for an application on the AM335x, 5) Linux, 6) RS-232 port for debug terminal, 7) USB port to use with Code Composer.

Any suggestions would be greatly appreciated.

Thanks,
Jeff

  • 0
    TI__Expert 3353 points

    Hello Jeff,

    Thanks for your question.  Agree, a lot to choose from. :-)  TI is committed to help customers with different system development tools targeted at different applications. Let me clarify and guide you to the right platform.

    For Industrial protocols like Modbus, you'd need a standard Ethernet i/f and a powerful, scalable processor like AM3352. Given that requirement and the other requirements you list, our $199 Starterkit EVM should be used. http://www.ti.com/tool/tmdssk3358

    In case you require more real-time Industrial protocols like Profibus or EtherCAT in slave function, then you'd need AM3356/7 which also have additional coprocessor called PRU-ICSS. ICE platform should be used for these applications.  http://www.ti.com/tool/tmdxice3359

    For Industrial drive applications, where you'd need Profibus/EtherCAT and also motor control capability, IDK platform can be used. IDK has all the hooks and  complementary TI technologies like C2000, CM3 to evaluate the entire Industrial drive application. http://www.ti.com/tool/tmdxidk3359

    Pl note that AM3352 and AM3356/7 and other 3 devices in the AM335x family are pin-to-pin compatible. So, you've a great degree of scalability for several Industrial applications.

    Hope this helps and let us know if any addln Qs.

    Thanks for considering TI products.

  • 0 in reply to Srik Gurrapu
    Intellectual 320 points

    Hi Srik,

    Thanks for the quick reply.   Does the $199 StarterKit EVM have RS-485 for Modbus RTU?  Or would I have to convert RS-232 to RS-485?

    Thanks,
    Jeff

  • 0 in reply to Jeff Stringer
    TI__Expert 3550 points

    Jeff,

    I looked through the block diagram;

    TMDSSK3358_V1_2A_Block_Diagram.JPG

    and it doesn't look like you really have access to a UART.  You could remove the WLAN module I suppose and tack a 485 driver to the UART pins... Likewise I guess you could pull the USB to serial adapter IC and hook in there; again the 485 driver would need to be added.  I just looked through the schematic too; short of pulling the component/module there;s no access; not even a series element to get to the UART pins. 

  • 0 in reply to radar
    Intellectual 320 points

    Thanks, that's good information.  I've been looking at the AM3359 Industrial Communications Engine (ICE) as well.  Looks like it doesn't support RS-485 directly but I may have access to the serial ports, so I could add a serial to RS-485 adapter.  What do you think?

  • 0 in reply to Jeff Stringer
    TI__Expert 3550 points

    That's even better; the AM3359 ICE is cheaper ($99) and yes, you do have access to serial ports.

  • 0 in reply to radar
    TI__Prodigy 335 points

    Hi Jeff,

    This is not a TI EVM, but as another option there is a popular BeagleBone development platform utilizing the AM335x devices from TI.

    http://beagleboard.org/bone

    There is a new RS485 add-on board called a Cape Board.

    http://circuitco.com/support/index.php?title=BeagleBone_RS485

    The site lists multiple suppliers and I don't advocate for any of them specifically, but this site did allow me to add the RS485 board to shopping cart so it appears to be available.

    http://boardzoo.com/advanced_search_result.php?keywords=RS485

    On the Modbus front, I am not aware of an available TI library for AM335, but here are a few links that may be a good place to begin looking.

    http://www.freemodbus.org/index.php?idx=5

    http://micrium.com/rtos/ucmodbus/drivers/

     

  • 0 in reply to Dave Baldwin
    Intellectual 320 points

    Thanks Dave.  That's good to know about the RS-485 for the BeagleBone.  One of the advantages of the ICE over the BeagleBone is that the ICE has 2 ports of Ethernet which may be important for us. 

  • 0 in reply to Jeff Stringer
    Prodigy 10 points

    I'm curious if the ICE is as open for development as the Beaglebone.  I'm currently using the Beaglebone for Modbus TCP with the pymodbus library.    I know that installing the python modules via Angstrom or Ubuntu is very easy, but don't have any experience with Sitara.  I'd like to give the ICE a try, but need access to certain libraries (unless the ICE has a dedicated Modbus Library).  

    Please advise.

    FYI.  Pymodbus is a fantastic module to use.  Incorporating database functions (logging) with python is very easy.  Many thanks to TI for offering solutions to Industrial Automation.  This is an area that has needed change. 

  • 0 in reply to Brandon Fowler
    TI__Mastermind 44306 points

    Brandon,

    of course ICE is open for development... you can find schematics and BOM on our web. Also it is supported by the IA-SDK software package. Difference here is that this SDK is Sys/Bios based (free TI RTOS) and not Linux. We do have solutions for PROFIBUS, EtherCAT and Ethernet/IP using PRU low level firmware now and are working one more.

    However Modbus/TCP doesn't seem to have such high real-time requirements as other industrial protocols. So it is assumed that available implementations based on Linux/python could be used on TI AM335x hardware with full Linux support (e.g. Starterkit, BeagleBone and BeagleBoneBlack). No work on Modbus/TCP has been done by us so far.

    Regards.

  • 0
    Prodigy 10 points

    Hello Jeff，

    Did you already found one suitable board which could meet all your demand?

    If not, I have some items to introduce you that all of them are designed by TI AM335x processor and with industrial grade configuration.

    single board computer OK335xD, OK335xS and OK335xS-II from Forlinx Embedded Tech. Co., Ltd.

    Rgds,

    Grace

    grace@forlinx.com