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Establish communication sequencer failure

Category: Datasheet/Specs
Product Number: MAX14819A

Hello, 

We are evaluating the MAX14189A (the EV kit) to be the physical controller of our io-link stack.
We are trying to test the establish-communication sequencer (auto detect)  but for some reason it is failing. We are 
using the io-link device transceiver utility to read and write to registers directly (without using our stack) just for this test.
The WURQInt is generated but the sequencer is failing to detect the correct COM baud rate. Same thing happens with or without the sensor. 
We are testing with PV7003 & IF6124 , both from IFM, but both are not detected. 
So is there an Application Note that can help? , if not, what should be the register settings for this test? 
We are using the default HW configuration of the EV kit. 

  • There are a few items to check:
    1. ESTCOM requires the framer to communicate, so the CLOCK must be configured correctly.
    Check if you are using an external crystal or an external oscillator which generates a waveform itself.
    Then configure the CLOCK register accordingly:

    2. TXENA and TXA should be both 0

    3. To send the ESTCOM sequence the Framer must be activated (register 0x0c = 0x42 for example).

    Please let me know if you considered all this.

    If you still have problems, then please send us your complete register configuration and explain the sequence of commands you're sending.

    Thanks and best regards,
    Konrad.

  • Hello 

    Thanks for your response. 
    I'm using the internal oscillator and here is the register settings. 

    I'm using the Evaluation Kit. 
    Every time I Set Establish Comm bit, I get an interrupt of WUREQ but the sensor is still not detected (COM bits are 00). 
    Please Advise on the correct sequence. 

  • Hello,

    the sequence isn't reallly a problem, everything needs to be configured before you set the ESTCOM bit.

    From your register settings above I can see:

    You need to configure the CQ Driver to be able to transmitt.
    I'd suggest to write Register 0x10 to 0x24.

    Everything else looks good at a first glance.

    Did you check if L+ is really available to the sensor after enabling L+?
    (Does the sensor get powered?)

    Are you able to look at the scope when you set the ESTCOM?
    If you look at the CQ to GND with a scope you should see the 80µs wake-up pulse followed by a message from the MAX14819.

    Then MAX14819 waits for a response and if there is none from the device, then it will resend the request in a lower COM rate and so on.

    Please check and let me know.

    Thanks and best regards,
    Konrad.

  • Hello Konrad, 

    Setting the 0x10 reg to 0x24 generated TX error interrupt. 
    I can also see that the COM baud rate changed to 11 (230.4 kbps). But that is not the baud rate of the PV7003 sensor. It is  38.4 kbps. 
    Plus the WUREQ interrupt was not generated. 
    The sensor is powered by the 24V coming from LA+. So no problem with power. 
    These are the registers and the HW connections. 

  • To me this sounds like there's something wrong with either your sensor or your sensor connection.

    One thing you could try. If you're using the MAX14819 EV-Kit + the GUI, then please click with your mouse onto the Tab "Register Settings". Then on the Keyboard push SHIFT+E, this will give you an additional Tab called Framer.

    Here you just click the following buttons:
    1. "Set DI high, L+ on, CQ PP and high"

    2. Set CQ PP and low

    3. Setup Framer

    4. Send ESTCOM

    Then the part should send a correct ESTCOM sequence.

    It would be helpful if you monitor the CQ pin with an oscilloscope.

    I hope this helps.
    Best regards,

    Konrad.