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DAC8742H: HART, FOUNDATIONFieldbus or PROFIBUS PA Device implementations

David Perez
Prodigy 210 points
Part Number: DAC8742H
Other Parts Discussed in Thread: PROFIBUS,

Hi to all,

We are working with one customer who is interested in developing a device that could support all the three protocols the DAC8742H offers. This part fit perfectly in their requirements. We are new to this field bus protocols so our initial doubt would be if there is any chance to get a unique hardware that can work with all the protocols, not obviously at the same time, using switches to select the specific protocol to use. The intention is to have a unique hardware device. avoiding creating different versions or BOMS.

In addition other doubt we have is if there is any kind of HART, Foundation Fielbus and Profibus PA libraries to implement the protocols comunications available. Do each developer need to create its own?

We would require, or customer, to join as members in the foundation/organizations to get access to any resource for developing? If somebody can help us clariying the path we should go through to develop a product which can comunicate in those field bus protocols we would appreciate it. We are considering to use a small MCU to develop the device field application.

Thanks in advance for your help us understanding or introducing to this new topic.

  • 0
    TI__Mastermind 30938 points

    Hi David, 

    Joe will review this and provide a response. 

    Best,

    Katlynne Jones 

  • 0
    TI__Guru* 93745 points

    David,


    The DAC874xH family of devices are basically modems. They take some signal and convert them to a different digital form to be read. For HART, it takes the frequency shift keyed signal and converts it to UART or SPI to be read. For Fieldbus or Profibus, I believe that it's a Manchester Encoded trapezoid to be converted to the UART or SPI. Profibus PA and Foundation Fieldbus (PA/FF) use the same physical layer. The DAC8742HEVM should be able to receive and transmit all of these signals. The EVM default configuration should be for HART. See below for the jumper configurations for PA/FF mode:

    JP1: (2-3), JP2: (2-3), JP3: open, JP4: (2-3)

    JP5: closed, JP6: (1-2), JP7: open, JP8: open

    JP9: (1-2), JP10: (1-2), JP11: (2-3), JP12: NC,

    JP13: open, JP14: (2-3), JP15: closed, JP16: (7-8)

    JP16: 7-8, JP17: closed, JP18: open, JP19: open, JP20: (1-2)

    In the EVM GUI enable the internal reference, internal BPF, and select PAFF mode. Then you should be able to load the write FIFO and click generate write to transmit. One way of checking is enabling FULL DUPLEX to read back the modulated waveform.

    To develop a device that uses HART, Fieldbus, or Profibus requires a lot of firmware development. For TI, we've done a design to make sure that the DAC874xH devices can be made to follow the HART protocol and had them registered with Fieldcomm Group. Fieldcomm Group oversees the HART protocol and registers HART device. However, we've used an outside vendor to develop the HART stack (the firmware implementation of the HART protocol). Note that we are not able to give out the firmware, and we don't have any example firmware to give out. The company that developed this firmware is Smart Embedded Systems in Fremont, California. You can see the TI design here:

    https://www.ti.com/lit/ug/tidudf6/tidudf6.pdf

    At the end of the design is a link to Smart Embedded Designs, and you can find out more from them.


    Joseph Wu

  • 0 in reply to Joseph Wu
    Prodigy 210 points

    Thanks!

    I have a better image of the required scope for these kind of developments.