I have a bunch of Keyence fiber optic sensors I'd like to use with my Arduinos. Model number fs-n11p it shows a max output amperage of 100 mA at 24v. What would I have to do to reduce that amperage down to 20 mA at 5v ensuring that the Arduino digital inputs can handle it? Can I just use a resistor that drops the voltage and current down to acceptable levels? Basically, what's the best way to use industrial type sensors with an Arduino or Raspberry Pi even?
Please post a link to the data sheet for the sensor.
Digital inputs draw no current. However, they must not be exposed to voltages above Vcc + 0.5V, so use a resistive voltage divider to reduce a 24V signal to the range of 4 to 5V (for a 5V Arduino).
A 10K:2.2K divider will reduce 24V to 4.3 V, suitable for a digital input on a 5V Arduino.
Curious, they way does the Arduino list "DC Current per I/O Pin 20 mA" under Tech Specs?
The link does not work for me.
Specifically for Arduino Uno and other AVR-based Arduinos:
Output pins should not be required to source or sink more than 20 mA, or they can be damaged.
Input pins draw no current (steady state) but must not be exposed to voltages above Vcc or below 0V.
If this really is an industrial application, use optoisolators on all logic connections. That way there is no electrical connection between the industrial side and the Arduino (hobby) side.
The voltage divider interface method requires all equipment to share a common ground, which in industrial environments can lead to ground loop induced noise and/or equipment failure.
Hi,
Your device will work down to 12V, but if you have 24V already available then use it.
In either case a potential divider will be needed.
Note that the output is PNP Open Collector so a pull down resistor is needed.
Tom... 
Tried to post a direct link to the datasheet download but didn't work apparently, here's an updated link to the product page and datasheet link.
Yes, I was researching optoisolators just verifying that was the correct path to take. I'm using a Rhino PSB24-120 24V 5A power supply. I have basically no experience with the Arduino at this point, I've only worked with industrial controls for the past several years.
So for outputs requiring more than 20mA are solid state relays the weapon of choice?
So for outputs requiring more than 20mA are solid state relays the weapon of choice?
You are making no sense. Please explain what you want to do.
If you want an Arduino output to control something, provide the data sheet for that something.
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