Universal Robots · Controlled Vocabulary
Universal Robots Vocabulary
Key industrial and robotics concepts covering Universal Robots cobots, their wire-level protocols, software stack, and ecosystem. Derived from publicly available Universal Robots developer documentation.
15 Terms
Updated
Universal Robots Vocabulary is a controlled vocabulary published by Universal Robots on the APIs.io network, defining 15 terms.
Defined terms include Cobot, RTDE, Dashboard Server, URScript, and URCap.
A controlled vocabulary pins the words an API’s schemas, parameters and documentation use to one agreed definition each — the shared language a human or an agent needs to read the API the same way its authors do.
Terms
Cobot
A collaborative robot (cobot) designed to operate safely alongside human workers in shared workspaces without requiring safety cages. Universal Robots manufactures cobots in the e-Series and UR-series product lines with payloads from 3 kg to 30 kg.
RTDE
Real-Time Data Exchange (RTDE) is Universal Robots' synchronous binary TCP protocol on port 30004. It enables external applications to stream robot state at 500 Hz (e-Series) or 125 Hz (CB3) and write input registers back into the controller. RTDE is the preferred integration channel for vision-guided motion, OEE telemetry, and ROS/ROS 2 drivers.
Dashboard Server
A plain-text TCP command interface on port 29999 that allows remote control of a UR robot: powering on/off, loading and playing programs, querying safety state, and managing installations. Dashboard Server is the simplest remote-control entry point and is suitable for MES integration.
URScript
URScript is Universal Robots' purpose-built domain-specific scripting language for cobot motion planning, I/O control, and process logic. Programs can be authored in the PolyScope teach pendant, streamed over the Secondary Client Interface, or generated by external tooling such as MoveIt or the ROS 2 driver.
URCap
A URCap is an installable software extension for Universal Robots cobots. The legacy URCap SDK (PolyScope 5) uses Java; the next-generation PolyScope X URCap SDK uses TypeScript/HTML with Docker-based containerization. URCaps add program nodes, installation screens, and hardware driver contributions (grippers, vision, screwdrivers) and are distributed through the UR+ marketplace.
PolyScope
PolyScope is the teach-pendant operating system software that runs on Universal Robots cobots. PolyScope 5 is the established version running on e-Series and CB3 robots; PolyScope X is the next-generation version for UR15, UR20, UR30, and newer cobots, featuring a rebuilt TypeScript/HTML architecture.
Primary Client Interface
A streaming binary TCP interface on port 30001 that emits robot state, configuration messages, and accepts URScript commands at 10 Hz. The Primary interface includes configuration data packets not available on other interfaces.
Secondary Client Interface
A streaming binary TCP interface on port 30002 operating at 10 Hz. The Secondary interface is the recommended channel for sending URScript programs and commands at runtime from external systems.
Tool Center Point (TCP)
The Tool Center Point (TCP) is the reference coordinate frame defined at the tip of the robot's end-effector. All motion commands and Cartesian-space trajectories are expressed relative to the TCP. Universal Robots cobots support multiple named TCP frames stored in the installation.
UR+ Ecosystem
The UR+ program is Universal Robots' certified third-party ecosystem of 500+ end-effectors, vision systems, software extensions, and URCap applications that are validated and distributed through the universal-robots.com/plus marketplace. UR+ partners develop accessories that integrate tightly with PolyScope and the robot's I/O system.
Joint State
The joint state is a vector of six values representing the angular position (radians), velocity (rad/s), and current (A) of each of the six revolute joints in a UR cobot. Joint state is continuously broadcast over the RTDE, Primary, Secondary, and Real-Time interfaces.
Safety State
The safety state reflects the current operational mode of the UR safety system, including normal operation, reduced mode, safeguard stop, emergency stop, and fault conditions. Safety state can be queried via the Dashboard Server and is broadcast in RTDE and interface packets.
Collaborative Operation
Collaborative operation refers to robot motion performed under ISO/TS 15066 safety-rated speed and force limits that allow humans and robots to share the same workspace simultaneously. Universal Robots cobots implement power-and-force limiting (PFL) to enable collaborative operation without perimeter guarding.
End-Effector
An end-effector (EOAT — end of arm tooling) is the device mounted at the robot's Tool Flange that interacts with the workpiece: grippers, welding torches, screwdrivers, cameras, or dispensers. UR cobots expose a tool flange (ISO 9409-1-50-4-M6) and a Tool Communication Interface (TCI) for end-effector power and data.
Real-Time Interface
The Real-Time Interface is a binary state streaming interface on port 30003 emitting robot state at 125 Hz (CB3) or 500 Hz (e-Series). It predates RTDE and is still supported for low-latency one-way state streaming; new integrations are recommended to prefer RTDE for its configurable schema and bidirectional capability.