If you would think to Google "4-20 mA receiver" you could learn a lot.
Peripheral IC's from TI and Maxim that have most everything you need all ready designed in. Modules you could interface to the BBB, etc. Application notes on how to design receivers, and things to worry about, common system problems that people have had with this circuit for the last 50 years. Good luck. == On Thursday, August 18, 2016 at 10:03:12 AM UTC-5, Przemek Klosowski wrote: > > On 8/17/2016 5:26 PM, [email protected] <javascript:> wrote: > >> I am wondering if a beaglebone black can be used to measure industrial >> 4-20 ma loops? I see there is an ADC feature, but the voltage range is >> only to 1.8V. Is it possible to set it up to work with the standard 24VDC >> circuitry involved with most 4-20ma loops? >> >> A 90 ohm resistor carrying 20mA will develop a voltage of 1.8V. This is > cutting it a little close, so I recommend 68 ohm, which is a more > standard/easier to find value anyway. So, just terminate your 4-20mA line > with this resistor, and connect it to the Beaglebone analog input. Of > course if you're in an industrial environment you need to watch out for > transients, noise and interference, especially since the Beaglebone inputs > are famously fragile, so include some serious input protection (e.g. four > diodes connected as two anti-parallel 2-diode chains, with a filter cap > across it and maybe some series resistance). Then again, you could follow > evilwulfie's advice to use a dedicated buffer op-amp. > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/00917cb1-80b6-4a82-9d78-e8a042f1d321%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
