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DAC8742HEVM: Can I use some teraterm terminal to read DAC8742HEVM HART by UART interface?

Part Number: DAC8742HEVM
Other Parts Discussed in Thread: DAC8742H

Can I use some teraterm terminal to read DAC8742HEVM HART by UART interface? Is there any instruction to access DAC8742HEVM UART interface from PC Serial port by Putty(terminal tool)?

I would like to get the transmitter HART data sending to AC8742EVM and read these transmitter data from PC serial port without using the provided DAC8742HEVM software. Thank you.

  • Hello,

    Yes, this should be possible. A USB to UART adapter will be required. You can connect to the UART pins on the J6 header and set the baud rate to 1200 in Putty. I can see this being valuable for receiving the HART data but it will not be possible to respond with the correct HART frame, as you can only send one command at a time through the terminal.

    Is there a reason you are not using the EVM software? It is quite simple to set up if you just want to send some basic HART data.

    Thanks,
    Garrett
  • Hi Garrett,

       Very thankful of your information. I don't use EVM software because I would like to read HART transmitter data from "COMMAND 3" to get PV, SV, TV, QV  by Raspberry Pi UART /ttyAMA0 interface.

    Can you explain why it is not possible to respond with correct HART frame? Is it because UART is Asynchronous that Master and Slave can not transmit/receive at the same time? But will it be possible

    that my PI can send "HART COMMAND 3" and wait for Slave DAC8742HEVM to reply the response from HART transmitter? In this case, how does PI send the Command request from Serial interface?

    Any library I have to pre-installed before sending command? It would be very helpful to help me receiving these plant industry transmitter data in IoT field. Thanks again.

  • Hello,

    I am not sure on the implementation with the RPi but the DAC8742H in UART mode just acts as a direct UART-HART converter. So writing UART data from the RPi at 1200bps will result in the corresponding HART waveform. It will be the same when receiving the HART data.

    My point about not being able to respond with the full HART frame was referring to using a terminal program to send the data over UART. I am not sure you could construct a full frame manually in the terminal. It is possible to do it with some script that receives the HART frame and responds with a predetermined HART frame.

    Thanks,
    Garrett
  • Hi Garrett, 

        Can I confirm the full HART frame you mean is like the below picture by sending HART message correctly, UART can receive HART response as you expected?

    Secondly, will UART have "hardware handshake" in Serial interface "RTS/CTS" like RS232 to negotiate sending message procedures? Thank you once again and wish you a good day.

  • Hello,

    Yes, you should be able to make the basic HART responses with some scripting.

    The DAC8742H will assert the CD pin when a carrier is detected. The RTS pin is used to enable the modulator as long as the demodulator is not active. The demodulation takes priority.

    Thanks,
    Garrett