about EPM240 high impedance output

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i think i havn't got the right answer

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In my opinion, you didn't manage to tell a clear question. It took three posts to clarify, that you showed expected rather than observed waveforms.

It's not necessary, that we understand the purpose of your circuit (which seems hard to get in terms of RS485 communication practice). We can reduce the discussion to a simple point: You're saying, that the high Z pin setting isn't working. You don't need all the RS485 circuitry and dynamic waveforms to check this. A static measurement should be sufficient. The voltage drop at the 3.3k resistor can tell most exactly, if the pin is sinking a current in the suspected case.