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 3, 2011 6:08 PM

    Hello Yurik,

    Thank you for the schematic and oscilloscope plot.

    Could I ask what data+/data- were connected to for the test condition? Were there any termination resistors, pull-up/pull-down on the bus, other nodes or cable?

    Also, does the half/full signal into the circuit switch between ADM2587E/ADM2484E at the time of the test, or will it have been stable (ADM2484E active) for some time before this?

    Regards,

    Conal

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  • 0
    •  Analog Employees 
    on Nov 3, 2011 6:08 PM

    Hello Yurik,

    Thank you for the schematic and oscilloscope plot.

    Could I ask what data+/data- were connected to for the test condition? Were there any termination resistors, pull-up/pull-down on the bus, other nodes or cable?

    Also, does the half/full signal into the circuit switch between ADM2587E/ADM2484E at the time of the test, or will it have been stable (ADM2484E active) for some time before this?

    Regards,

    Conal

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