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About sha102

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    Hi, I am New!

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  1. PLC digital input resistors

    Thanks a lot for your responses.  I thought the digital inputs have internal pull up or is that installed externally? About wiring, Please see attached image. My understanding is that R3 is internal and I would like to find the value of that. I looked at Siemens S7 datasheet. Based on the DO numbers,  R3 would be 8k. Voltage simulations shows PLC input is not getting close to 0 V in low state. I am concerned that the threshold wont be met and be detected by the PLC as a low.
  2. hello everyone , I am involved in the development of an industrial  product. It has a 24 V On / OFF  output signal which will be read by a PLC digital input. It could be Allen Bradley / Siemens .  Can anyone tell me what would be the approximate values of the internal pull ups and pull downs? where can i find this? Thank you for all the help.  Regards Sha