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TIOL111: IO Link design question

Part Number: TIOL111

At the pictures the green/blue is measured at CQ the purple is WAKE and the yellow is NFAULT the blue is just to ignore

First picture is what I am measuring at CQ line of a TIOL111DMWT, I cant figure out why my WAKE and NFAULT is reaction as they are. The ILIM_ADJ is connected to GND(L-) the wakeup signal is looking funny, but it transceiver acknowledge it, (if I remove the CQ line from the TIOL and measure at it un -loaded the wake up signal goes from 0 to 24Vdc in 80 usec and returns to zero).

If the ILIM_ADJ is op instead it reacts as the picture below. Any ideas to why the wake up signal looks as it does? and why the WAKE and NFAULT is reacting as they do?

  • Hi Lasse,

    In the first picture it looks like the CQ line is initially low, which I am assuming is because the TIOL111 device is enabled and pulling CQ down. At about -1.5 x-axis divisions on the scope, the CQ line gets pulled to slightly higher voltage - this should be the partner device signaling a wake-up request via driving the opposite logic state for 80 us. At this point, the WAKE pin goes low to signal a wake request has been received. However, it looks like TIOL111 remains enabled for some time, and during this time the partner device repeatedly drives an opposite state (forcing a current over the configured limit). By about -1 x-axis division, it looks like one of these high-current pulses occurs with long-enough duration to be considered an over-current fault, and so the NFAULT pin asserts low accordingly.

    In the second picture the WAKE behavior is the same but the NFAULT behavior is a little bit different. When the ILIM pin is open it enables a mode where the automatic output shut-off and re-enabling is disabling, allowing for some flexibility in driving loads that may require higher currents for longer periods. In this case the over-current indication via NFAULT is immediate and does not require a certain overcurrent duration. That's why in the second picture you see NFAULT assert low each time the partner device tries to drive the CQ line high.

    I hope this is all clear, and please just let me know if you have further questions.

    Regards,
    Max
  • Hi again 

    You are writing "At this point, the WAKE pin goes low to signal a wake request has been received. However, it looks like TIOL111 remains enabled for some time". The enable pin is constantly HIGH in my test setup, does this give some problems? If i am diabling the Enable pin, the NFAULT pin will be disabled aswell and wouldnt that be bad, because when I am receiving a package it will not be possible to see if there is any errors, or am I misunderstanding what the NFAULT pin is used too?

    The other possible configuration as I see it, is a HIGH enable pin until the wake-up irq, then the enable pin should go LOW while receiving and HIGH again when it has to transmit the respond. Or can you maybe describe to me, when the different pins has to be high or low? 

  • Lasse,

    Keeping EN high until a wake-up occurs and then pulling it low while the partner device transmits over the CQ line is the right configuration. Otherwise, keeping EN high would result in both ends of the link trying to drive CQ simultaneously, and this would corrupt the data. NFAULT reporting is not so critical when the driver is disabled since the indicator is not for data errors but instead fault conditions (like output over-current, device over-temperature, etc.).

    Regards,
    Max