{"id":3622,"date":"2026-10-29T14:45:58","date_gmt":"2026-10-29T06:45:58","guid":{"rendered":"http:\/\/www.epitexespana.com\/blog\/?p=3622"},"modified":"2026-10-29T14:45:58","modified_gmt":"2026-10-29T06:45:58","slug":"what-output-signals-do-optical-level-sensors-provide-46e6-6b22ac","status":"publish","type":"post","link":"http:\/\/www.epitexespana.com\/blog\/2026\/10\/29\/what-output-signals-do-optical-level-sensors-provide-46e6-6b22ac\/","title":{"rendered":"What output signals do optical level sensors provide?"},"content":{"rendered":"

Hey there, if you\u2019re working with liquid level monitoring\u2014whether it\u2019s for industrial tanks, food and beverage processing, or even lab equipment\u2014you know how critical it is to get clear, reliable data fast. As someone who supplies optical level sensors for a living, I run into this question all the time: \u201cWhat output signals do these things actually put out?\u201d It\u2019s not just a random detail\u2014getting the right signal for your setup means the difference between a system that runs like a well-oiled machine and one that\u2019s causing headaches at 2 a.m. when a tank overflows. Let\u2019s break this down like we\u2019re chatting over a coffee, no super jargon (okay, maybe a little, but I\u2019ll explain it). Optical Level Sensor<\/a><\/p>\n

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First off, let\u2019s keep it simple: optical level sensors work by using light, usually an LED beam and a photodetector. When light hits a liquid surface vs. air, it reflects or refracts differently\u2014so the sensor \u201csees\u201d whether there\u2019s liquid where it\u2019s mounted. But what happens next is where the output signal comes in. That\u2019s how the sensor communicates that level info to your PLC, controller, or monitoring system. And yeah, I\u2019ve seen way too many people pick a sensor just based on the light tech, only to realize they didn\u2019t check if the signal plays nice with their existing gear. That\u2019s a miss, so let\u2019s cover the main ones we supply, no fluff.<\/p>\n

The most common one you\u2019ll run into is digital output. Let\u2019s split that into two types because they\u2019re not the same: discrete (or on\/off) digital, and PWM (pulse-width modulation) digital. Discrete is the basics\u2014this is the \u201cis it full or empty?\u201d signal. Think of it like a light switch: the sensor sends a high signal (usually 5V or 24V, depending on your power setup) when it detects liquid, and a low signal when it doesn\u2019t. Or vice versa, depending on how you wire it. For a lot of small tanks, like in a brewery\u2019s fermenter, that\u2019s all you need\u2014you just want an alert when the liquid hits a certain spot, so the pump turns on or off. We sell a ton of these for that exact use case; they\u2019re cheap, easy to install, and no need for extra processing.<\/p>\n

Then PWM digital is a step up. Instead of just on\/off, it sends a square wave where the length of the pulse (the width) changes based on the liquid level. Higher liquid level = wider pulse, lower = narrower. This isn\u2019t just a binary yes\/no\u2014it gives you a rough analog-like reading without having to handle an actual analog signal. It\u2019s great for systems where you need to track how full a tank is over time, like a chemical storage tank where you can\u2019t just rely on two trigger points. I remember a customer who used our PWM optical sensor for their rainwater harvesting system; they programmed a controller to read the pulse width, so it automatically routed water to different tanks depending on how full each was. Saved them so much manual checking, they called it a game-changer.<\/p>\n

Next up, analog output\u2014this is the one that\u2019s like a slow, steady signal that\u2019s proportional to level. The two big ones here are 4-20 mA current loop and 0-10V DC voltage. Let\u2019s talk 4-20 mA first because it\u2019s the workhorse for industrial stuff. The beauty of current is that it\u2019s not affected by wire length or electrical noise, which is huge when you\u2019re running wires 100+ feet across a plant. 4 mA is usually \u201cempty\u201d and 20 mA is \u201cfull\u201d\u2014so if your sensor sends 12 mA, that\u2019s exactly halfway. No conversion needed, your controller can read that directly. We use this for most of our industrial-grade optical sensors; oil refineries, wastewater treatment plants, even pharmaceutical companies swear by it because it\u2019s consistent. I had a customer in the food industry who switched from ultrasonic sensors to our 4-20 mA optical ones because the ultrasonic kept messing up with foam from mixing; the optical got a clear light reflection, and the 4-20 signal stayed rock solid no matter the foam.<\/p>\n

0-10V DC is simpler for smaller setups, like lab equipment or small process tanks. Here, 0V is empty and 10V is full. It\u2019s easier to wire than 4-20 mA (no extra current loop wiring needed) but it\u2019s more prone to noise over long distances, so it\u2019s best for setups under 50 feet. We keep a lot of these in stock for universities that need level sensors in their lab bioreactors\u2014their small systems don\u2019t need the extra noise protection, and the voltage signal works right with their small controllers.<\/p>\n

Wait, are there other outputs? Yeah, I\u2019ve seen some specialty ones, like IO-Link. That\u2019s a newer digital standard that\u2019s super handy for Industry 4.0 setups. It doesn\u2019t just send on\/off or level info\u2014it can send diagnostic data, like if the LED is dying, or if there\u2019s dust blocking the lens, or how many cycles the sensor has run. That\u2019s massive for predictive maintenance\u2014you don\u2019t wait for the sensor to fail, you get a heads up it\u2019s time to replace it. We\u2019ve had a couple of manufacturing clients adopt these for their assembly line tank systems; they\u2019ve cut unplanned downtime by almost 30% just from using the diagnostic data from the IO-Link output.<\/p>\n

Now, let\u2019s be real\u2014why does this matter for you, not just tech specs? If you pick a sensor with a 4-20 mA output but your controller only takes 0-10V, you\u2019re gonna waste time and money trying to add a converter. If you need to monitor 10 different tanks from a central screen, a discrete sensor won\u2019t give you enough data to show each tank\u2019s level, just when it hits a threshold. I\u2019ve had so many people come to me saying they had a bad experience with optical sensors, and 9 times out of 10 it\u2019s because they grabbed the wrong output for their setup. Like that one guy who tried to use a discrete output sensor for his 500-gallon diesel tank\u2014he only knew if it was above or below a set point, not how much fuel he actually had. He switched to our 4-20 mA model and hasn\u2019t looked back.<\/p>\n

Also, let\u2019s not forget to mention that a lot of our sensors are configurable\u2014you can switch between outputs, or adjust the sensitivity, right from the controller or a little app. That\u2019s a big plus when your needs change later. Maybe you start with a discrete output for a small tank, then expand to a larger system that needs analog\u2014you don\u2019t have to replace the whole sensor, just tweak the settings. We do that on most of our mid-range optical level sensors, which is why a lot of repeat customers come back.<\/p>\n

Wait, should I touch on how the output ties to the sensor\u2019s other features? Like, if you\u2019re dealing with liquids that have foam, high viscosity, or are translucent, the optical sensor\u2019s light type (infrared vs. visible red) will affect the signal, but the output signal still follows the same main types. We make sensors with both infrared (better for opaque liquids, less visible to passersby) and visible red (cheaper, good for clear liquids), but the output\u2014digital, PWM, 4-20, 0-10V\u2014stays consistent. That\u2019s one less thing to worry about when choosing.<\/p>\n

Now, if you\u2019re in the market for an optical level sensor, don\u2019t overcomplicate it. First, figure out two things: 1) do you just need to know when liquid is at a certain point, or do you need a continuous level reading? 2) how far is the sensor from your controller, and what type of signals does your controller already use? If it\u2019s just on\/off, discrete is fine. If continuous, go for 4-20 mA for long wires, 0-10V for short. If you want smart diagnostics, IO-Link is worth the extra buck.<\/p>\n

We supply all of these\u2014from basic discrete sensors for small DIY projects up to industrial-grade 4-20 mA and IO-Link ones for big factories. If you\u2019re stuck on what\u2019s right for your setup, reach out to us and we can walk through it no problem. No sales pitch pressure, just actual advice from people who install these every day. That\u2019s the thing about working with a supplier that\u2019s hands-on\u2014we don\u2019t just sell parts, we know how they work in real situations.<\/p>\n

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Now, a quick note to wrap up: optical level sensors are awesome because they\u2019re non-contact (most of them, anyway\u2014wait, no, the ones we supply are usually mounted on the outside of the tank or dipped in, but no moving parts so no wear), so they last longer than float sensors or ultrasonic ones in harsh environments. But the output signal is what makes them work with your system. Don\u2019t sleep on that detail.<\/p>\n

Float Level Sensor<\/a> If you\u2019re ready to pick a sensor or want to chat through your specific needs, get in touch to discuss. We\u2019ll make sure you get the right output signal and the right sensor for your use case.
\nReferences<\/p>\n

    \n
  1. Fraden, J. (2016). Handbook of Modern Sensors: Physics, Designs, and Applications. Springer.<\/li>\n
  2. International Electrotechnical Commission (IEC). (2020). IEC 61508: Functional Safety of Electrical\/Electronic\/Programmable Electronic Safety-related Systems.<\/li>\n
  3. Optek Technology. (2022). Optical Level Sensor Application Guide. Littelfuse, Inc.<\/li>\n
  4. Industry 4.0 Initiatives. (2021). IO-Link Standard for Smart Sensor Communication. International Society of Automation (ISA).<\/li>\n<\/ol>\n
    \n

    Shenzhen Fineherc Technology Co., Ltd.<\/a>
    As one of the most experienced optical level sensor suppliers in China, we’re featured by quality products and low price. Please feel free to buy discount optical level sensor made in China here from our factory. Welcome to view our website for more information.
    Address: 5th Floor, Building D, No. 39, Keji East Road, Torch Development Zone, Zhongshan City,China
    E-mail: fineherc@hotmail.com
    WebSite:     https:\/\/www.fineherc.com\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

    Hey there, if you\u2019re working with liquid level monitoring\u2014whether it\u2019s for industrial tanks, food and beverage … What output signals do optical level sensors provide?<\/span>Read more<\/a><\/p>\n","protected":false},"author":614,"featured_media":3622,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[3585],"class_list":["post-3622","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry","tag-optical-level-sensor-4384-6b5c01"],"_links":{"self":[{"href":"http:\/\/www.epitexespana.com\/blog\/wp-json\/wp\/v2\/posts\/3622","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.epitexespana.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.epitexespana.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.epitexespana.com\/blog\/wp-json\/wp\/v2\/users\/614"}],"replies":[{"embeddable":true,"href":"http:\/\/www.epitexespana.com\/blog\/wp-json\/wp\/v2\/comments?post=3622"}],"version-history":[{"count":0,"href":"http:\/\/www.epitexespana.com\/blog\/wp-json\/wp\/v2\/posts\/3622\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.epitexespana.com\/blog\/wp-json\/wp\/v2\/posts\/3622"}],"wp:attachment":[{"href":"http:\/\/www.epitexespana.com\/blog\/wp-json\/wp\/v2\/media?parent=3622"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.epitexespana.com\/blog\/wp-json\/wp\/v2\/categories?post=3622"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.epitexespana.com\/blog\/wp-json\/wp\/v2\/tags?post=3622"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}