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TIOL111: EN function

Nam, Dino
Expert 6445 points
Part Number: TIOL111

Dear team, 

My customer want to know about EN function, 

1. At datasheet, When EN is Low, Device is only receive mode. This mean the data can't transmit from slave(TIOL111x) to master through C/Q line.  Is it right?

2. When EN is high,  Can TIOL111x operate as an receiver and transmitter through C/Q line? or Does TIOL111x operate only as a transmitter? 

3. If TIOL111x operate only transmitter when EN is high, how can this device receive data from master and how can recognize when master transmit data through C/Q line? 

Thank  you. 

  • 0
    TI__Guru 62920 points
    Hi Dino,

    You are right that when EN is low, the transmit function is disabled but the receiver remains active. The receiver also stays active when the transmitter is enabled via pulling EN high and will continue to reflect the logic state represented on the CQ line. If the master tries to initiate communication with the slave while the slave transmitter is active, there will be some contention on the CQ line that may result in undefined CQ voltage levels. However, the master should start transmission using a WAKE request, and the TIOL111 recognizes the overcurrent condition resulting from this request and signals it via the WAKE output. Therefore, it is good to monitor both RX and WAKE if the application needs to allow for a master node to initiate communication to the slave while the slave output is active.

    Please just let me know if this isn't clear or if you have further questions.

    Regards,
    Max
  • 0 in reply to Miguel Robertson
    TI__Expert 6445 points
    Hi Max,

    Thank you for your comment. One more question.
    At datasheet mentioned, The IO-Link communication specification requires the device node to switch to receive mode within 500 μs after receiving the wake-up signal.
    If the TIOL111 detects this wake-up signal when EN signal is high, local micro controller switch EN signal from High to Low with 500 us. Is it right?
    If not, does micro controller monitor only RX signal when wake-up signal is detected without EN switching(high to low)?
    Thank you.
  • 0 in reply to Nam, Dino
    TI__Expert 6445 points

    Hi Max, 

    Thank you for your comment. One more question. 
    At datasheet mentioned, The IO-Link communication specification requires the device node to switch to receive mode within 500 μs after receiving the wake-up signal.
    If the TIOL111 detects this wake-up signal when EN signal is high, local micro controller switch EN signal from High to Low with 500 us. Is it right? 
    If not, does micro controller monitor only RX signal when wake-up signal is detected without EN switching(high to low)?

    Thank you

  • 0 in reply to Nam, Dino
    TI__Guru 62920 points
    Dino,

    The microcontroller would need to switch to receive-only mode by pulling EN low. Communication would not work reliably with both master and slave/device transmitters active on the same line, and so the WAKE signal is used to signal to the slave side that it needs to disable its transmitter.

    Max
  • 0 in reply to Miguel Robertson
    TI__Expert 6445 points
    Hello Max,

    Thank you for your quick response.
    Assume EN =high, but If transmitter data of slave is none, Can slave receive data from master although EN is high?

    Thank you.
  • 0 in reply to Nam, Dino
    TI__Guru 62920 points
    Dino,

    No, as long as EN is high the CQ output from the slave will either be driven high or low via a low-impedance output driver (high-side or low-side switch). This would interfere with communication from the master. (For example, if the TX input to TIOL111 were held low while EN was high, the slave output would be pulled high. If the master side tried to pull the line low, then, it would need to contend with the slave output. This would result in higher current flow and an undefined voltage level on the line. This is why the WAKE request is needed.)

    Max