From working on controls on ships. Measuring the current using a CT (current transformer) or Rogowski coil to measure the current is a fairly standard way to monitor if something actually turned on when you told it to. A coil is a fairly robust device (no moving parts) so fairly reliable although sometime the connections become loose or the small wires susceptible to vibrations and breaking depending on the application. If you choose to use a CT make sure to never have a live conductor in it without it being connected to a rated measurement device reading. Since it’s a transformer, as current goes to zero, voltage goes to infinity which is generally a large value before it gets to be exciting.
There are also devices called wire break detectors that are wired in series (I think they’re a type of galvanic isolator) that can be used to monitor if there’s a break in the wire but some of the cheaper ones are not as robust and have had them fail.
Physical movement there are a lot of limit switches. Rotary encoders and rheostats are another way to monitor rotation of an object. I’ve even seen a rheostat used as a switch in a safety critical system before when they didn’t want to risk an open circuit, so just measuring resistance above or below a certain threshold was on or off.
Smart camera systems with computer vision are becoming more main stream.
Industrial sensors are often 4..20mA. Below 4 mA you might have a break or noise. If your reading is above 20mA you might have a short or noise. Slightly above or below might be a calibration issue.
Your acceptable rate and mode of failure will dictate what kind and how many layers of monitoring you need.
Depending on your use case you might be able to set up a camera and computer running openCV to watch the led and see if it comes on.
From working on controls on ships. Measuring the current using a CT (current transformer) or Rogowski coil to measure the current is a fairly standard way to monitor if something actually turned on when you told it to. A coil is a fairly robust device (no moving parts) so fairly reliable although sometime the connections become loose or the small wires susceptible to vibrations and breaking depending on the application. If you choose to use a CT make sure to never have a live conductor in it without it being connected to a rated measurement device reading. Since it’s a transformer, as current goes to zero, voltage goes to infinity which is generally a large value before it gets to be exciting. There are also devices called wire break detectors that are wired in series (I think they’re a type of galvanic isolator) that can be used to monitor if there’s a break in the wire but some of the cheaper ones are not as robust and have had them fail. Physical movement there are a lot of limit switches. Rotary encoders and rheostats are another way to monitor rotation of an object. I’ve even seen a rheostat used as a switch in a safety critical system before when they didn’t want to risk an open circuit, so just measuring resistance above or below a certain threshold was on or off. Smart camera systems with computer vision are becoming more main stream. Industrial sensors are often 4..20mA. Below 4 mA you might have a break or noise. If your reading is above 20mA you might have a short or noise. Slightly above or below might be a calibration issue.
Your acceptable rate and mode of failure will dictate what kind and how many layers of monitoring you need.
Depending on your use case you might be able to set up a camera and computer running openCV to watch the led and see if it comes on.