need help with ADM2484E

Have received a problem at use ADM2484E - the starting bit turns out with  "step". The circuit drawing and signal photo in the appendix. In the photo:

- blue signal (3) - transmission enable - pin 5 DE ADM2484E

- green (2) - TxD signal on 6 pin of ADM2484E

- yellow (1) - RS485 line signal (DATA+ pin 14 ADM2485E)

Thanks!

attachments.zip
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  • 0
    •  Analog Employees 
    on Nov 7, 2011 5:57 PM

    Hello Yuri,

    If I understand correctly then, the behaviour in the oscilloscope plot you provided is not present if the circuit is connected only to the bus without the other two nodes? This would suggest the ADM2484E is operating correctly.

    Is it possible to check if this occurs with only the TAU circuit and one of the other nodes connected (and termination resistors) and not the other node. And vice-versa as well?

    One of the nodes does have an "automatic flow control" feature, perhaps the unexpected "high" is due to an error in this? (unexpected bus contention)

    Regards,

    Conal

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  • 0
    •  Analog Employees 
    on Nov 7, 2011 5:57 PM

    Hello Yuri,

    If I understand correctly then, the behaviour in the oscilloscope plot you provided is not present if the circuit is connected only to the bus without the other two nodes? This would suggest the ADM2484E is operating correctly.

    Is it possible to check if this occurs with only the TAU circuit and one of the other nodes connected (and termination resistors) and not the other node. And vice-versa as well?

    One of the nodes does have an "automatic flow control" feature, perhaps the unexpected "high" is due to an error in this? (unexpected bus contention)

    Regards,

    Conal

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