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Original question:

THVD8010: THVD8010

THVD8010: signal of THVD8010

user6421271
Prodigy 50 points
Part Number: THVD8010

signal of THVD8010.pdf

  • 0
    TI__Guru 69522 points

    User,

    An engineer has been notified of this post and will respond tomorrow when TI's offices open.

    Regards,

    Eric Hackett 

  • 0
    TI__Mastermind 25705 points

    Hi,

    Can you check if any termination resistors are populated in the system? The termination value matches cable impedance. 

    The communication can work with hundreds of meters cable with 300kHz (table 2 of the design guide). When checking the amplitude, please refer to the ground nearby. I hope this helps. BTW, what's the cable length between TP2 and  TP3? 

  • 0
    Prodigy 50 points

    Can you check if any termination resistors are populated in the system? The termination value matches cable impedance. 

      There is no terminal resistance here. The wiring at the installation site is very complicated. I think it is difficult to know the resistance value. Do you have suggestions?  I changed the coupling capacitor from 1u to 0.47u, will it help reduce noise ?

    The communication can work with hundreds of meters cable with 300kHz (table 2 of the design guide). When checking the amplitude, please refer to the ground nearby. I hope this helps. BTW, what's the cable length between TP2 and  TP3? 

      I know the table 2, we are going to reduce the frequency, hope it will be longer,     it is 1 meter from TP2 to TP3.  We measure the signal at each node with itself GND.  

      I measured the received signal from slave node on the master node. It is small and sometimes cannot be demodulated.

      Whether the inductance value is too large is at the slave node. It is 4.7mH. According to this table, 330uH  is also ok, I want to try. The PCBA of all nodes is the same.   

      

  • 0 in reply to user6421271
    TI__Mastermind 25705 points

    Thanks for your information. Like RS-485, if there is main bus, you can use termination to match the cable impedance. Even you don't know the cable impedance, some value between 80Ohm to 120Ohm can be used. Some termination is always better than open end.

    Bigger inductor should only help here. I suggest you check the signal integrity with the basic setup (point to point, no power delivery). If there is only cable loss in communication, the received signal should look clean with smaller amplitude and slower edges.