ERD Symbols and Meanings

The vector stencils library "Dimensioning and tolerancing" contains 45 symbols of geometric dimensions and mechanical tolerances, geometric symbols, callouts, and text boxes and inserts.
Use these geometric dimensioning and tolerancing (GD&T) shapes to create annotated mechanical drawings.
"Geometric dimensioning and tolerancing (GD&T) is a system for defining and communicating engineering tolerances. It uses a symbolic language on engineering drawings and computer-generated three-dimensional solid models that explicitly describes nominal geometry and its allowable variation. It tells the manufacturing staff and machines what degree of accuracy and precision is needed on each controlled feature of the part. GD&T is used to define the nominal (theoretically perfect) geometry of parts and assemblies, to define the allowable variation in form and possible size of individual features, and to define the allowable variation between features." [Geometric dimensioning and tolerancing. Wikipedia]
The shapes example "Design elements - Dimensioning and tolerancing" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Mechanical Engineering solution from the ConceptDraw Solution Park.

The vector stencils library "Switches and relays" contains 58 symbols of electrical contacts, switches, relays, circuit breakers, selectors, connectors, disconnect devices, switching circuits, current regulators, and thermostats for electrical devices.
"In electrical engineering, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another.
The most familiar form of switch is a manually operated electromechanical device with one or more sets of electrical contacts, which are connected to external circuits. Each set of contacts can be in one of two states: either "closed" meaning the contacts are touching and electricity can flow between them, or "open", meaning the contacts are separated and the switch is nonconducting. The mechanism actuating the transition between these two states (open or closed) can be either a "toggle" (flip switch for continuous "on" or "off") or "momentary" (push-for "on" or push-for "off") type.
A switch may be directly manipulated by a human as a control signal to a system, such as a computer keyboard button, or to control power flow in a circuit, such as a light switch. Automatically operated switches can be used to control the motions of machines, for example, to indicate that a garage door has reached its full open position or that a machine tool is in a position to accept another workpiece. Switches may be operated by process variables such as pressure, temperature, flow, current, voltage, and force, acting as sensors in a process and used to automatically control a system. ... A switch that is operated by another electrical circuit is called a relay. Large switches may be remotely operated by a motor drive mechanism. Some switches are used to isolate electric power from a system, providing a visible point of isolation that can be padlocked if necessary to prevent accidental operation of a machine during maintenance, or to prevent electric shock." [Switch. Wikipedia]
"A relay is an electrically operated switch. Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such as solid-state relays. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal. The first relays were used in long distance telegraph circuits as amplifiers: they repeated the signal coming in from one circuit and re-transmitted it on another circuit. Relays were used extensively in telephone exchanges and early computers to perform logical operations.
A type of relay that can handle the high power required to directly control an electric motor or other loads is called a contactor. Solid-state relays control power circuits with no moving parts, instead using a semiconductor device to perform switching. Relays with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical circuits from overload or faults; in modern electric power systems these functions are performed by digital instruments still called "protective relays"." [Relay. Wikipedia]
The shapes example "Design elements - Switches and relays" was drawn using the ConceptDraw PRO diagramming and vector drawing software extended with the Electrical Engineering solution from the Engineering area of ConceptDraw Solution Park.

The vector stencils library "Transmission paths" contains 43 symbols of power transmission paths, electronic circuits, bus connectors and elbows, terminals, junctions, and concentrators.
Use it to annotate electrical diagrams, electronic schematics and circuit diagrams.
"A physical medium in data communications is the transmission path over which a signal propagates.
Many transmission media are used as communications channel.
For telecommunications purposes in the United States, Federal Standard 1037C, transmission media are classified as one of the following:
(1) Guided (or bounded) - waves are guided along a solid medium such as a transmission line.
(2) Wireless (or unguided) - transmission and reception are achieved by means of an antenna.
One of the most common physical medias used in networking is copper wire. Copper wire to carry signals to long distances using relatively low amounts of power. The unshielded twisted pair (UTP) is eight strands of copper wire, organized into four pairs.
Another example of a physical medium is optical fiber, which has emerged as the most commonly used transmission medium for long-distance communications. Optical fiber is a thin strand of glass that guides light along its length.
Multimode and single mode are two types of commonly used optical fiber. Multimode fiber uses LEDs as the light source and can carry signals over shorter distances, about 2 kilometers. Single mode can carry signals over distances of tens of miles.
Wireless media may carry surface waves or skywaves, either longitudinally or transversely, and are so classified.
In both communications, communication is in the form of electromagnetic waves. With guided transmission media, the waves are guided along a physical path; examples of guided media include phone lines, twisted pair cables, coaxial cables, and optical fibers. Unguided transmission media are methods that allow the transmission of data without the use of physical means to define the path it takes. Examples of this include microwave, radio or infrared. Unguided media provide a means for transmitting electromagnetic waves but do not guide them; examples are propagation through air, vacuum and seawater.
The term direct link is used to refer to the transmission path between two devices in which signals propagate directly from transmitters to receivers with no intermediate devices, other than amplifiers or repeaters used to increase signal strength. This term can apply to both guided and unguided media.
A transmission may be simplex, half-duplex, or full-duplex.
In simplex transmission, signals are transmitted in only one direction; one station is a transmitter and the other is the receiver. In the half-duplex operation, both stations may transmit, but only one at a time. In full duplex operation, both stations may transmit simultaneously. In the latter case, the medium is carrying signals in both directions at same time." [Transmission medium. Wikipedia]
The shapes example "Design elements - Transmission paths" was drawn using the ConceptDraw PRO diagramming and vector drawing software extended with the Electrical Engineering solution from the Engineering area of ConceptDraw Solution Park.

The vector stencils library "Process annotations" contains 22 symbols of interface points, slope, off-sheet labels, callouts and textboxes.
Use these shapes for setting automatic labels to display a datasheet field for a pipeline shape, labels, captions, outlines, off-sheet labels, text balloons, annotations, outlines, tags, and descriptions.
"In engineering a process is a set of interrelated tasks that, together, transform inputs into outputs. These tasks may be carried out by people, nature, or machines using resources; so an engineering process must be considered in the context of the agents carrying out the tasks, and the resource attributes involved. Systems Engineering normative documents and those related to Maturity Models are typically based on processes. For example, System Engineering processes of the EIA-632 and processes involved in the Capability Maturity Model Integration (CMMI) institutionalization and improvement approach. Constraints imposed on the tasks and resources required to implement them are essential for executing the tasks mentioned.
A chemical process is a series of unit operations used to produce a material in large quantities.
In the chemical industry, chemical engineers will use the following to define or illustrate a process:
Process Flow Diagram (PFD),
Piping and instrumentation diagram
(P&ID),
Simplified process description,
Detailed process description,
Project management,
Process simulation." [Process (engineering). Wikipedia]
The example "Design elements - Process annotations" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Chemical and Process Engineering solution from the Engineering area of ConceptDraw Solution Park.

The vector stencils library "Vessels" contains 40 symbols of vessels, containers, tanks, drums, and basins.
Use these shapes for drawing process flow diagrams (PFD), materials handling systems, and feed systems in industrial and manufacturing processes.
"A pressure vessel is a closed container designed to hold gases or liquids at a pressure substantially different from the ambient pressure.
The pressure differential is dangerous and fatal accidents have occurred in the history of pressure vessel development and operation. Consequently, pressure vessel design, manufacture, and operation are regulated by engineering authorities backed by legislation. For these reasons, the definition of a pressure vessel varies from country to country, but involves parameters such as maximum safe operating pressure and temperature." [Pressure vessel. Wikipedia]
The example "Design elements - Vessels" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Chemical and Process Engineering solution from the Engineering area of ConceptDraw Solution Park.

The vector stencils library "Ports and Flows" contains 26 SysML symbols.
Use it to design your SysML diagrams using ConceptDraw PRO diagramming and vector drawing software.
"The main motivation for specifying ports and flows is to enable design of modular, reusable blocks with clearly defined
ways of connecting and interacting with their context of use. This clause extends UML ports to support nested ports, and
extends blocks to support flow properties, and required and provided features, including blocks that type ports. Ports can be typed by blocks that support operations, receptions, and properties as in UML. SysML defines a specialized form of Block (InterfaceBlock) that can be used to support nested ports. SysML identifies two kinds of ports, one that exposes
features of the owning block or its internal parts (proxy ports), and another that supports its own features (full ports). Default compatibility rules are defined for connecting blocks used in composite structure, including parts and ports, with association blocks available to define more specific ways of doing this. These additional capabilities in SysML enable modelers to specify a wide variety of interconnectable components, which can be implemented through many engineering and social techniques, such as software, electrical or mechanical components, and human organizations. This clause also extends UML information flows for specifying item flows across connectors and associations." [www.omg.org/ spec/ SysML/ 1.3/ PDF]
The SysML shapes example "Design elements - Ports and Flows" is included in the SysML solution from the Software Development area of ConceptDraw Solution Park.

"Crow's Foot notation is used in Barker's Notation, SSADM and Information Engineering. Crow's Foot diagrams represent entities as boxes, and relationships as lines between the boxes. Different shapes at the ends of these lines represent the cardinality of the relationship." [Entity–relationship model. Wikipedia]
The vector stencils library ERD, crow's foot notation contains 18 symbols for creating the ER-diagrams using the ConceptDraw PRO diagramming nd vector drawing software.
The example"Design elements - ERD solution (crow's foot notation)" is included in the Entity-Relationship Diagram (ERD) solution from the Software Development area of ConceptDraw Solution Park.

The vector stencils library "Video and audio" contains 50 symbols of audio and video devices and equipment.
Use the design elements library "Video and audio" for drawing audio and video system layouts, cabling floor plans, electrical circuit schematics and wiring diagrams of video and sound reproduction systems using the ConceptDraw PRO diagramming and vector drawing software.
Using the "Video and audio" library you can create video and audio engineering drawings and layout plans of your digital and analog, stereophonic (stereo), high fidelity (Hi-Fi, or hifi), quadraphonic, surround-sound, and home audio systems, home entertainment systems, home cinema (home theater, or home theatre), high-definition television (HDTV) and 3D television systems.
The shapes library "Video and audio" is included in the Electric and Telecom Plans solution from the Building Plans area of ConceptDraw Solution Park.