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Author Topic: Input pin issues...?  (Read 2636 times)

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Input pin issues...?
« on: March 22, 2013, 09:14:53 AM »
I have an e-stop switch wired to PIN10 as shown in the image:
Switch connected to +5V source, 3.9K pulldown to GND and 220ohm resistor on the input pin for current limiting.
This setup is not working because when the switch is closed I am reading proper 5V on the input, but when it is open the voltage stays at ~2v instead of 0.
Is there a strong pullup on the serial port?
How should this be setup?

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Re: Input pin issues...?
« Reply #1 on: March 23, 2013, 03:41:50 AM »
Hi Boris,

I doubt that there is a pull-up on the computer’s LPT parallel port (although you could possibly have a bad Pin 10). There are, however, often a pull-up’s on the inputs to the breakout board / controller board.

I suggest that you wire your e-stop so that it takes pin 10 to ground with a pull-up to +5 if necessary then configure e-stop as Active Low.