[{"data":1,"prerenderedAt":293},["ShallowReactive",2],{"blog-types-of-ot-devices-a-reference-guide":3,"authors":142},{"id":4,"title":5,"author":6,"body":7,"categories":115,"category":116,"date":117,"description":118,"extension":119,"featured":120,"fields":115,"image":121,"keyTakeaways":115,"meta":122,"modified":115,"navigation":123,"path":124,"seo":125,"slug":126,"stem":127,"tags":128,"__hash__":141},"blog\u002Fblog\u002Ftypes-of-ot-devices-a-reference-guide.md","Types of OT Devices: A Reference Guide to the Operational Technology Landscape","FirstWave Team",{"type":8,"value":9,"toc":105},"minimark",[10,14,17,22,25,28,31,34,38,41,44,47,50,53,57,60,63,66,69,73,76,80,83,86,90,93],[11,12,13],"p",{},"If you have an IT background, operational technology might seem unfamiliar. The acronyms are new, and the priorities shift to safety and uptime instead of confidentiality. The hardware also has names you probably have not seen when managing servers and laptops. But OT now often shares the same networks that IT teams are asked to secure and monitor. So, understanding the different types of OT devices is now essential for anyone managing a combined environment.",[11,15,16],{},"This guide explains the OT landscape in simple terms. It covers the main types of OT devices, what they do, and how they relate to each other. The Purdue model is the main framework used here. It organizes industrial systems into levels, from the physical process at the bottom to the enterprise at the top. You do not need to memorize the model, but it helps show how everything fits together.",[18,19,21],"h2",{"id":20},"the-field-layer-sensors-and-actuators-purdue-level-0","The Field Layer: Sensors and Actuators (Purdue Level 0)",[11,23,24],{},"At the lowest level, right next to the physical process, are field devices. These are the simplest and most common OT devices, and they come in two types.",[11,26,27],{},"Sensors measure something about the physical world and report it. A temperature sensor on a reactor, a pressure transmitter on a pipeline, a flow meter on a water main, a level sensor in a tank, a proximity switch on a conveyor. Their whole job is to turn a physical quantity into a signal a controller can read.",[11,29,30],{},"Actuators do the opposite: they take a command and produce a physical action. A motor that drives a pump, a control valve that opens or closes to regulate flow, a valve positioner, a relay, a variable-speed drive. When a controller decides the tank is too full, it is an actuator that actually closes the valve.",[11,32,33],{},"Everything above this layer exists to read these sensors and command these actuators. If you have ever wondered what a network of industrial controllers is ultimately for, this is the answer: measuring and moving the physical world.",[18,35,37],{"id":36},"the-control-layer-plcs-rtus-and-ieds-purdue-level-1","The Control Layer: PLCs, RTUs and IEDs (Purdue Level 1)",[11,39,40],{},"One level up sit the controllers - the devices that read the sensors, run the logic, and drive the actuators in real time. This is the heart of industrial automation, and it is where most of the well-known OT acronyms live.",[11,42,43],{},"PLC (Programmable Logic Controller). The workhorse of factory and process automation. A PLC is a ruggedized, deterministic controller that scans its inputs, runs a control program, and updates its outputs on millisecond cycles, over and over, reliably, for years. If a machine on a production line starts, stops, or interlocks based on conditions, a PLC is almost certainly making that decision.",[11,45,46],{},"RTU (Remote Terminal Unit). Think of an RTU as a PLC built for distance and isolation. RTUs connect field sensors and actuators to a central supervisory system over long-haul links - cellular, radio, satellite, or wired Ethernet - which makes them the natural fit for geographically spread infrastructure like pipelines, water networks, and electrical distribution. Where a PLC lives on a plant floor, an RTU often lives in a cabinet at a remote site nobody visits for months.",[11,48,49],{},"IED (Intelligent Electronic Device). A term you will hear most in the power and utility world. An IED is a microprocessor-based device embedded in equipment such as a circuit breaker, transformer, or protective relay. It monitors its equipment, makes local protective decisions, and reports upstream. IEDs are, in effect, specialized controllers with a protection and metering job.",[11,51,52],{},"PAC (Programmable Automation Controller). Worth a mention because the line between PLC and PAC has blurred. A PAC is essentially a higher-end controller that combines PLC-style control with more advanced computing, networking, and data handling, often used where a single device needs to do more than classic ladder-logic control.",[18,54,56],{"id":55},"the-supervisory-layer-hmis-scada-and-dcs-purdue-level-2","The Supervisory Layer: HMIs, SCADA and DCS (Purdue Level 2)",[11,58,59],{},"Controllers run the process, but people still need to watch it and intervene. That is the supervisory layer, and it is where humans meet the machines.",[11,61,62],{},"HMI (Human-Machine Interface). The screen an operator actually looks at. An HMI displays live process data - tank levels, temperatures, pump states - as graphics, alarms, and trends, and lets the operator issue commands. It is the window into the process and the steering wheel, usually running on a panel or an industrial workstation next to the equipment.",[11,64,65],{},"SCADA (Supervisory Control and Data Acquisition). Not a single device but a system, and one of the most important terms in OT. SCADA ties the layers together: it gathers data from field instruments and controllers, presents it through HMIs and a central master station, stores history, and lets operators supervise processes that may be spread across a city or a continent. SCADA is the classic architecture for distributed infrastructure - utilities, water, oil and gas - where you are monitoring many remote sites from one control room.",[11,67,68],{},"DCS (Distributed Control System). SCADA's close cousin, optimized for a different problem. Where SCADA excels at geographically distributed sites, a DCS is built for a single large facility with many tightly coupled control loops running at once - a chemical plant, refinery, or power station. Control is distributed across cooperating controllers within the plant, all coordinated under one system. The rough rule of thumb: SCADA for wide-area supervision, DCS for dense in-plant process control.",[18,70,72],{"id":71},"the-safety-layer-safety-instrumented-systems","The Safety Layer: Safety Instrumented Systems",[11,74,75],{},"Cutting across the layers above is a category that deserves its own heading because its whole reason for existing is to be separate. A Safety Instrumented System (SIS) is a dedicated, independent system whose only job is to bring a process to a safe state when something goes wrong - shutting down a reactor before pressure becomes dangerous, for example. An SIS has its own sensors, its own logic solver, and its own actuators, deliberately kept apart from the normal control system so that a failure in day-to-day control cannot disable the safety net. In plants handling toxic, flammable, or explosive materials, the SIS is the last line of defense, and its independence is the entire point.",[18,77,79],{"id":78},"the-connective-tissue-gateways-historians-and-industrial-network-gear","The Connective Tissue: Gateways, Historians and Industrial Network Gear",[11,81,82],{},"A few more device types round out the picture, because OT does not run on controllers alone.",[11,84,85],{},"Protocol gateways and converters translate between the many industrial protocols - Modbus, DNP3, PROFINET, EtherNet\u002FIP, OPC UA and others - so devices that were never designed to talk to each other can share data. Historians are specialized databases that record process data over time for analysis, reporting, and compliance. Industrial switches, routers and firewalls are the ruggedized network equipment that moves all this traffic in environments too hot, cold, or electrically noisy for ordinary IT gear. And increasingly, IIoT devices and edge gateways - smart sensors and small compute nodes that connect newer equipment straight to analytics platforms - sit alongside the traditional stack, often bypassing the neat Purdue hierarchy entirely.",[18,87,89],{"id":88},"why-the-mix-matters","Why the Mix Matters",[11,91,92],{},"The main point is not to remember all the acronyms, but to understand the structure. OT is a layered system: sensors and actuators interact with the physical world, controllers handle real-time logic, supervisory systems let people monitor and control, and a separate safety layer is always ready to step in. Many of these devices were designed years ago, use protocols without built-in security, and were never meant to share a network with email or web browsers. As IT and OT come together, this mix will be on your network, whether you know it or not. You cannot monitor, secure, or manage devices you do not recognize.",[11,94,95,96,101,102,104],{},"The first step is knowing what these devices are. The next step is finding out which ones you actually have, and this is where many organizations realize their asset inventory ends at the IT boundary. Agentless discovery tools like ",[97,98,100],"a",{"href":99},"\u002Fdownload\u002F","Open-AudIT"," can help you see all connected devices, so OT devices on your network appear as recognized assets instead of blind spots. Try ",[97,103,100],{"href":99}," when you are ready to turn this guide into your own inventory.",{"title":106,"searchDepth":107,"depth":107,"links":108},"",2,[109,110,111,112,113,114],{"id":20,"depth":107,"text":21},{"id":36,"depth":107,"text":37},{"id":55,"depth":107,"text":56},{"id":71,"depth":107,"text":72},{"id":78,"depth":107,"text":79},{"id":88,"depth":107,"text":89},null,"Industry","2026-09-03","Operational technology runs on a device zoo most IT teams never learned - PLCs, RTUs, HMIs, SCADA, DCS, IEDs, and the sensors and actuators beneath them. 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Recognised by the AFR as one of Australia's Top 100 Women of Influence in Technology and Innovation. Industry Fellow at Griffith University.",{"title":106,"searchDepth":107,"depth":107,"links":269},[],{"linkedin":271},"https:\u002F\u002Fwww.linkedin.com\u002Fin\u002Fsharonhunneybell\u002F",{},"\u002Fauthors\u002Fsharon-hunneybell","VP of Products",{"title":261,"description":267},"sharon-hunneybell","authors\u002Fsharon-hunneybell","Technology leader with over 20 years in the industry, and an Industry Fellow at Griffith University.","tlbya__xxsO4vAF3WX8gNdnlgdxP-NuSHGQSKO1Zhgs",{"id":281,"title":282,"aliases":115,"avatar":115,"body":283,"description":106,"extension":119,"inactive":120,"kind":115,"links":115,"meta":287,"navigation":123,"path":288,"role":115,"seo":289,"slug":290,"stem":291,"tagline":115,"__hash__":292},"authors\u002Fauthors\u002Fsimon-may.md","Simon May",{"type":8,"value":284,"toc":285},[],{"title":106,"searchDepth":107,"depth":107,"links":286},[],{},"\u002Fauthors\u002Fsimon-may",{"title":282,"description":106},"simon-may","authors\u002Fsimon-may","0in6dS2PIxCquqjG_2uCTM8PAw3O1xyMGHfcNRgCm8w",1788507213235]