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DAC161S997: Query regarding loop error generation.

Ankush
Prodigy 250 points
Part Number: DAC161S997

Hi Team, 

I'm using dac161s997 Ic for 4-20mA output generation.

I want to use the ERRB PIN for showing "loop open" message on my device but the ERRB PIN always stays pulled down whether the loop is closed or open.

Any idea where i m going wrong?

Thanks Ankush.

  • 0
    TI__Guru 53183 points

    Hi Ankush,

    Do you have a pull-up resistor on the ERRB pin? A pull-down resistor?

    Thanks,

    Paul

  • 0 in reply to Paul_Frost
    Prodigy 250 points

    Hi Paul ,

    I have Pull-up resistor on ERRB Pin  and MCU connected to that pin as input pin .
    I have also configure DIS_LOOP_ERR_ERRB to zero( 0 ) in ERR_CONFIG register but still it is low for both condition weather the loop is connected or open .

  • 0 in reply to Ankush
    TI__Mastermind 29258 points

    Hi Ankush,

    A few members of our team are traveling/out of office. They will be able to get back to you on Monday. 

    Best,

    Katlynne Jones 

  • 0 in reply to Katlynne Jones
    TI__Guru 53183 points

    Hi Ankush,

    Just to double check - if you disconnect the input pin from ERRB pin, does it have the same behavior?

  • 0 in reply to Paul_Frost
    Prodigy 250 points

    Hi Paul ,

     I have disconnected ERRB pin from MCU and checked but still its same ,ERRB pin is low irrespective of loop is connected or open . 

  • 0 in reply to Ankush
    TI__Guru 53183 points

    okay, let me confer with my colleagues.

  • 0
    TI__Guru* 93425 points

    Ankush,


    First, I would check the physical connections to ERRB to make sure the pull-up is properly connected and that the ERRB pin isn't accidentally grounded because of solder bridge.

    How much current is in your loop? Is it the correct value when operating?

    The ERRB pin can be pulled low for several different reasons. For this device, there could be a loop error (as you had mentioned). There could also be a frame error, where the write to the device is incorrect. There could also be an SPI timeout error, where the device has not received an SPI communication within a timeout period. There are several different ways to test which is the real problem. In Section 8.4 for Device Functional Modes on page 9 of the datasheet there's a table of errors, and how they are reported.

    First you can read the STATUS register to see what errors are being flagged. Each of the three errors are reported in the status register. Second, you could disable the ERRB reporting for the loop error and the SPI timeout error through the ERR_CONFIG register.

    I believe that the SPI timeout is enabled by default. I would disable it in ERR_CONFIG and set MASK_SPI_TOUT to 1 (page 14 of the datasheet). Let me know if this is the problem. If not, we can continue working on it.


    Joseph Wu