Using an SSR photoelectric sensor with Arduino

Question

I'm wondering if I can use this photoelectric sensor with an Arduino. I don't have much experience with these sensors or with relays, and I'm sometimes confused by output switch ratings, so I can use the help.

Here's my understanding. Two of the sensor's cables are for power supply. The other two are listed as "isolated AC/DC outputs" and I want to connect those to an Arduino to detect the sensor's state change. The data sheet says "Output Load:  300mA @ 240 VAC/VDC." I think that means the maximum rating. My question is, if an Arduino only sources 40mA at 5V, do I need to figure out if there is a minimum requirement for sensor's outputs? And if so, how do I do that?

Answer 1

Thanks for the responses to my question. I'm answering my own question because I was able to do some further research into this specific unit. Instead of getting limited answers through the vendor's tech support, I eventually found Eaton, the company that produces this item, and spoke to their extremely helpful sensor tech support person.

So the basic answer is yes, powered separately, the unit can be used with an Arduino. I should've clarified better that I was mainly concerned about using an Arduino with the unit's outputs. He confirmed that the unit's outputs are isolated from the power supply and can work with either AC or DC, so no conversion to DC is necessary. The outputs function as a switch contact whose state the Arduino could read directly. That said, tech support did still recommend the mechanical relay version as another user pointed out. Despite isolation on the outputs, there could be some current leakage with an SSR, whereas there shouldn't be any with the mechanical relay version, and my application is not a super-high-processing environment where a mechanical version would soon fail from wear and tear on the physical contacts (using the example he gave, not a UPS shipping facility where they would need a much longer-lasting SSR-version sensor to count tens of thousands of packages a shift).

Answer 2

Short answer is anything will work with anything if you try hard enough. This product with JUST the Arduino will NOT work. This SSR is just too industrial and is not designed in the slightest to be put together with the Arduino.

There are simply no areas that allow you to easily sense the status of the relay.

If you are insistent on making this work with the Arduino, you'll need to:

• First, supply the SSR with a 12v power source
• Second, convert the AC output of the relay to DC
• Lastly, buck the DC voltage down to 5V

Once you have that, you can effectively sense the output of the SSR.

In all seriousness though, I would advise looking for a much more application-fit relay if you have to use an Arduino. I would suspect there are some sort of PLCs for use with industrial relays such as this.

Answer 3

I would prefer the -6514 version, with "real" relay contacts as outputs. I wouldn't trust an SSR designed to work with 120 - 240 AC/DC to work reliably with the 5 volt inputs on an Arduino.

Answer 4

If your goal is a just a photoelectric sensor that triggers a logic signal on an Arduino, you can do this with a few dollars worth of parts, fed from the 5V regulated power supply out of the Arduino.

You'd use an IR LED as the light source. Then you'd use an IR phototransistor as the sensor. Feed that into the gate of an NPN transistor. Then you'd feed the output of that to the Arduino.

The total list of parts: A high output IR LED. An IR Phototransistor. A general purpose low-power NPN transistor. 2 or 3 resistors. Plus a reflector or some reflective tape if want the sensor to be all together in a box. Plus a breadboard or prototype board, some jumper wires, and a project box.

The company HiViz.com sells kits and assembled circuits designed to trigger cameras and flashes, but it would be trivial to adapt it to control a logic input on an Arduino. (The camera and flash circuits use an opto isolator to isolate potentially high voltage flashes from the other electronics, but if this is purely powered by the Arduino, you won't need that.)

I just built a prototype circuit like the one I described using just an NPN transistor, a photogate, some resistors, and a breadboard. If you're interested let me know and I can figure out how to create and upload a schematic. (I haven't tried using the web-based schematic editor before, but I can probably figure it out.)