OT Glossary

Highway addressable remote transducer

A protocol used in process industries that allows digital communication with instruments over the same wires as analog signals. Many analog field instruments (like pressure transmitters) use a 4-20 mA signal to indicate value, but with HART, they can also superimpose a digital signal on top of that current loop. This lets operators or control systems talk to the device, reading diagnostics, setting ranges, etc., without extra wiring. Think of HART as giving your “dumb” analog sensor a way to speak up and say more than just its measurement, all over the existing cable.

Hazard and operability study

A structured approach for examining a process or system to identify potential hazards and operability problems. In industrial contexts, a HAZOP is done by a team brainstorming “what if” scenarios for each part of a process (e.g. “What if valve X fails closed?”) to foresee what could go wrong. While HAZOP itself is a process safety technique (ensuring the process is designed safely), it’s increasingly being adapted to consider cybersecurity (e.g. what if a hacker did X). 

A specialized database system for time-series data in industrial environments. A historian continuously collects and stores chronological data from the process, things like temperatures, pressures, flow rates, equipment statuses, etc., often at high frequency. These databases are optimized for time-stamped data and for rapid retrieval of trends. They’re crucial for analysis, troubleshooting, and regulatory reporting in industrial operations.

Human machine interface - Visually represents the current state of a process, typically providing operators some way to interact with the process as well (change set points, open/close valves, start/top equipment...).

A decoy system or server set up to attract attackers, so their techniques can be studied. In OT, a honeypot might mimic a PLC or a SCADA server to lure in would-be intruders. Researchers deploy ICS honeypots that emulate vulnerable control systems to see how attackers behave when they think they’ve found an exposed power plant or factory. The honeypot has no real control over a process. It’s a trap, and any interaction with it is by definition suspicious, since legitimate users wouldn’t normally be there.

A major ICS vendor known for DCS and process control systems (Experion), as well as building automation.