My device's documentation says to "please provide a 820 ohm minimum pull-up resistor" for this schematic. Isn't the point of a pull-up resistor to enable us to differentiate between floating and open states? If my application is not concerned with such a thing, do I really need to include this? My primary reservation in not doing so is that I worry it is offering me some sort of current protection, although in a switched state there would be no such protection. This is for a turbine flow meter. I am not seeing any information regarding protecting the magnetic pickup inside this turbine flow meter as far as current limitation goes. Resistor in series, maybe? Or should I look to my current sourcing input module to provide an internal resistance? Would most people agree this is a standard feature in most modern PLC modules?
Thanks,
Mel
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Thanks,
Mel
Mods Note:
Before you upload the photos, please compress to a clear resolution as 800x600 or 1024x768, this photo already compressed to 800x492 and the file size from around 2.9MB to 61KB.