My current project has a little hitch and i'm not sure there is a way to configure a device as wanted but thought i would probe here for answers.
Essentially i have a 4-20 signal between a sensor and communication device leading into a PLC. I would like a little nano every to read this and then represent it as a percent on a screen at the request of a momentary switch. Fairly easy thankfully. The issue arises thus that i am fully aware that 4-20 must be read in series as it is current based but i would like to leave the original signal as untouched as possible rather than feeding it through an arduino.
The easy solution would to have the comms device feed a 4-20 back into the Arduino but im being difficult/ system limitations.
Basically i want to ascertain is there a device or method im lacking to read but not interrupt a 4-20mA signal between the sensor and the destination.
To be honest i really should have considered this in the first place. Thank you. Working it out in my head would you agree that this configuration could work without interfering in the original signal? or does this in practice make things go awry?
Connect the 4-20mA signal to one end of A 250 Ohm resistor.
Connect the other end of the resistor to analog input pin (e.g., A0).
Connect the ground of the 4-20mA signal to the Arduino ground.
Id use a 1K resistor but most important, the Arduino must be battery operated or supplied via an isolated power supply.
The voltage you read will depend on how the PLC reads the current.