According to the IEC standard, % is a prefix that identifies internal memory addresses in the logic controller to store the value of program variables, constants, I/O, and so on.
Converts received voltage or current levels into numerical values. You can store and process these values within the logic controller.
Converts numerical values within the logic controller and sends out proportional voltage or current levels.
A program including configuration data, symbols, and documentation.
(bootstrap protocol) A UDP network protocol that can be used by a network client to automatically obtain an IP address (and possibly other data) from a server. The client identifies itself to the server using the client MAC address. The server, which maintains a pre-configured table of client device MAC addresses and associated IP addresses, sends the client its pre-configured IP address. BOOTP was originally used as a method that enabled diskless hosts to be remotely booted over a network. The BOOTP process assigns an infinite lease of an IP address. The BOOTP service utilizes UDP ports 67 and 68.
(bit per second) A definition of transmission rate, also given in conjunction with multiplicator kilo (kbps) and mega (mbps).
The process of setting or maintaining the accuracy of a measuring device by comparing its value to a known and correct standard.
(continuous function chart) A graphical programming language (an extension of the IEC 61131-3 standard) based on the function block diagram language that works like a flowchart. However, no networks are used and free positioning of graphic elements is possible, which allows feedback loops. For each block, the inputs are on the left and the outputs on the right. You can link the block outputs to the inputs of other blocks to create complex expressions.
The arrangement and interconnection of hardware components within a system and the hardware and software parameters that determine the operating characteristics of the system.
continuous function chart language
A graphical programming language (an extension of the IEC61131-3 standard) based on the function block diagram language that works like a flowchart. However, no networks are used and free positioning of graphic elements is possible, which allows feedback loops. For each block, the inputs are on the left and the outputs on the right. You can link the block outputs to inputs of other blocks to create complex expressions.
A network containing logic controllers, SCADA systems, PCs, HMI, switches, ...
Two kinds of topologies are supported:
oflat: all modules and devices in this network belong to same subnet.
o2 levels: the network is split into an operation network and an inter-controller network.
These two networks can be physically independent, but are generally linked by a routing device.
(dynamic host configuration protocol) An advanced extension of BOOTP. DHCP is more advanced, but both DHCP and BOOTP are common. (DHCP can handle BOOTP client requests.)
(Deutsches Institut für Normung) A German institution that sets engineering and dimensional standards.
(electronic industries alliance rack) A standardized (EIA 310-D, IEC 60297, and DIN 41494 SC48D) system for mounting various electronic modules in a stack or rack that is 19 inches (482.6 mm) wide.
In a programmable controller system, most electronic modules directly interface to the sensors, actuators, and external devices of the machine/process. This electronic module is the component that mounts in a bus base and provides electrical connections between the controller and the field devices. Electronic modules are offered in a variety of signal levels and capacities. (Some electronic modules are not I/O interfaces, including power distribution modules and transmitter/receiver modules.)
EN identifies one of many European standards maintained by CEN (European Committee for Standardization), CENELEC (European Committee for Electrotechnical Standardization), or ETSI (European Telecommunications Standards Institute).
A part of a machine including sub-assemblies such as conveyors, turntables, and so on.
A physical and data link layer technology for LANs, also known as IEEE 802.3.
FAST input/output Specific I/O modules with some electrical features (for example, response time) while the treatment of these channels are done directly by the controller
(function block diagram) One of 5 languages for logic or control supported by the standard IEC 61131-3 for control systems. Function block diagram is a graphically oriented programming language. It works with a list of networks, where each network contains a graphical structure of boxes and connection lines, which represents either a logical or arithmetic expression, the call of a function block, a jump, or a return instruction.
(functional Earth) A common grounding connection to enhance or otherwise allow normal operation of electrically sensitive equipment (also referred to as functional ground in North America).
In contrast to a protective Earth (protective ground), a functional earth connection serves a purpose other than shock protection, and may normally carry current. Examples of devices that use functional earth connections include surge suppressors and electromagnetic interference filters, certain antennas, and measurement instruments.
(frequency generator) A function that generates a square wave signal with programmable frequency.
A programming unit that has 1 input and returns 1 immediate result. However, unlike FBs, it is directly called with its name (as opposed to through an instance), has no persistent state from one call to the next and can be used as an operand in other programming expressions.
Examples: boolean (AND) operators, calculations, conversions (BYTE_TO_INT)
Rectangular connector for electrical signals with frequencies below 3 MHz, complying with IEC 60807-2.
(human machine interface) An operator interface (usually graphical) for human control over industrial equipment.
(high-speed counter) A function that counts pulses on the controller or on expansion module inputs.
(input/output)
(input/output terminal) A collection of connection points between the field wiring and the I/O modules or those integrated into the controller.
(international electrotechnical commission) A non-profit and non-governmental international standards organization that prepares and publishes international standards for electrical, electronic, and related technologies.
Part 3 of a 3-part IEC standard for industrial automation equipment. IEC 61131-3 is concerned with controller programming languages and defines 2 graphical and 2 textual programming language standards. The graphical programming languages are ladder diagram and function block diagram. The textual programming languages include structured text and instruction list.
(instruction list) A program written in the language that is composed of a series of text-based instructions executed sequentially by the controller. Each instruction includes a line number, an instruction code, and an operand (refer to IEC 61131-3).
A collection of connection points between the field wiring and the I/O modules or those integrated into the controller.
A program written in the instruction list language that is composed of a series of text-based instructions executed sequentially by the controller. Each instruction includes a line number, an instruction code, and an operand (see IEC 61131-3).
(Internet protocol Part of the TCP/IP protocol family that tracks the Internet addresses of devices, routes outgoing messages, and recognizes incoming messages.
(ingress protection) The protection classification according to IEC 60529 offered by an enclosure, shown by the letter IP and 2 digits. The first digit indicates 2 factors: helping protect persons and for equipment. The second digit indicates helping protect against water. IP 20 devices help protect against electric contact of objects larger than 12.5 mm, but not against water.
A graphical representation of the instructions of a controller program with symbols for contacts, coils, and blocks in a series of rungs executed sequentially by a controller (see IEC 61131-3).
(ladder diagram) A graphical representation of the instructions of a controller program with symbols for contacts, coils, and blocks in a series of rungs executed sequentially by a controller (refer to IEC 61131-3).
(light emitting diode) An indicator that illuminates under a low-level electrical charge.
Consists of several functions and/or equipment.
The single direction of control in a network that implements the master/slave mode.
The protocol that allows communications between many devices connected to the same network.
(millisecond)
(normally open) A contact pair that opens when the actuator is de-energized (no power is applied) and closes when the actuator is energized (power is applied).
(national electrical manufacturers association) The standard for the performance of various classes of electrical enclosures. The NEMA standards cover corrosion resistance, ability to help protect from rain, submersion, and so on. For IEC member countries, the IEC 60529 standard classifies the ingress protection rating for enclosures.
A system of interconnected devices that share a common data path and protocol for communications.
An addressable device on a communication network.
A collection of connection points between the field wiring and the I/O modules or those integrated into the controller.
(Protective Earth) A common grounding connection to help avoid the hazard of electric shock by keeping any exposed conductive surface of a device at earth potential. To avoid possible voltage drop, no current is allowed to flow in this conductor (also referred to as protective ground in North America or as an equipment grounding conductor in the US national electrical code).
The power supply is connected to these terminals to provide power to the controller.
The component of an application that consists of compiled source code capable of being installed in the memory of a logic controller.
A convention or standard definition that controls or enables the connection, communication, and data transfer between 2 computing system and devices.
(pulse width modulation) A fast output that oscillates between off and on in an adjustable duty cycle, producing a rectangular wave form (though you can adjust it to produce a square wave).
Among the outputs of HSC are the reflex outputs associated to a threshold value that is compared to the counter value depending on the configuration of the HSC. The reflex outputs switch to either on or off depending on the configured relationship with the threshold.
A standard type of 8-pin connector for network cables defined for Ethernet.
A standard type of serial communication bus, based on 2 wires (also known as EIA RS-485).
(real-time clock) A battery-backed time-of-day and calender clock that operates continuously, even when the controller is not powered for the life of the battery.
A command that causes the controller to scan the application program, read the physical inputs, and write to the physical outputs according to solution of the logic of the program.
A function that includes:
oreading inputs and placing the values in memory
oexecuting the application program 1 instruction at a time and storing the results in memory
ousing the results to update outputs
(sequential function chart) A language that is composed of steps with associated actions, transitions with associated logic condition, and directed links between steps and transitions. (The SFC standard is defined in IEC 848. It is IEC 61131-3 compliant.)
(structured text) A language that includes complex statements and nested instructions (such as iteration loops, conditional executions, or functions). ST is compliant with IEC 61131-3.
A command that causes the controller to stop running an application program.
A group of sections and subroutines, executed cyclically or periodically for the master task, or periodically for the periodic task.
A task possesses a priority level and is linked to the I/Os of the logic controller. These I/Os are refreshed in consequence.
A logic controller can have several tasks.
(transmission control protocol) A connection-based transport layer protocol that provides a simultaneous bi-directional transmission of data. TCP is part of the TCP/IP protocol suite.
(terminal block) The component that mounts in an electronic module and provides electrical connections between the controller and the field devices.
