Converts numerical values within the logic controller and sends out proportional voltage or current levels.
A program including configuration data, symbols, and documentation.
The collection of human-readable controller instructions, configuration data, HMI instructions, symbols, and other program documentation. The application source file is saved on the PC and you can download the application source file to most logic controllers. The application source file is used to build the executable program that runs in the logic controller.
(address resolution protocol) An IP network layer protocol for Ethernet that maps an IP address to a MAC (hardware) address.
(binary coded decimal) The format that represents decimal numbers between 0 and 9 with a set of 4 bits (a nybble/nibble, also titled as half byte). In this format, the 4 bits used to encode decimal numbers have an unused range of combinations.
For example, the number 2,450 is encoded as 0010 0100 0101 0000.
(boolean) A basic data type in computing. A BOOL variable can have one of these values: 0 (FALSE), 1 (TRUE). A bit that is extracted from a word is of type BOOL; for example, %MW10.4 is a fifth bit of memory word number 10.
(boot application) The binary file that contains the application. Usually, it is stored in the controller and allows the controller to boot on the application that the user has generated.
(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.
A type that is encoded in an 8-bit format, ranging from 00 hex to FF hex.
(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.
Automates industrial processes (also known as programmable logic controller or programmable controller).
(cyclical redundancy check) A method used to determine the validity of a communication transmission. The transmission contains a bit field that constitutes a checksum. The message is used to calculate the checksum by the transmitter according to the content of the message. Receiving nodes, then recalculate the field in the same manner. Any discrepancy in the value of the 2 CRC calculations indicates that the transmitted message and the received message are different.
The controller logs events relative to the user application in a data log.
A network that contains devices connected to a specific communication port of a logic controller. This controller is seen as a master from the devices point of view.
(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.)
(double integer type) Encoded in 32-bit format.
(domain name system) The naming system for computers and devices connected to a LAN or the Internet.
(device type manager) Classified into 2 categories:
oDevice DTMs connect to the field device configuration components.
oCommDTMs connect to the software communication components.
The DTM provides a unified structure for accessing device parameters and configuring, operating, and diagnosing the devices. DTMs can range from a simple graphical user interface for setting device parameters to a highly sophisticated application capable of performing complex real-time calculations for diagnosis and maintenance purposes.
(double word) Encoded in 32-bit format.
(electronic data sheet) A file for fieldbus device description that contains, for example, the properties of a device such as parameters and settings.
A device for length or angular measurement (linear or rotary encoders).
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.
An electronic communication bus between expansion I/O modules and a controller or bus coupler.
(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.
Represents the BIOS, data parameters, and programming instructions that constitute the operating system on a controller. The firmware is stored in non-volatile memory within the controller.
A non-volatile memory that can be overwritten. It is stored on a special EEPROM that can be erased and reprogrammed.
When a logic controller is in freewheeling scan mode, a new task scan starts as soon as the previous scan has been completed. Contrast with periodic scan mode.
(frequency generator) A function that generates a square wave signal with programmable frequency.
(file transfer protocol) A standard network protocol built on a client-server architecture to exchange and manipulate files over TCP/IP based networks regardless of their size.
Rectangular connector for electrical signals with frequencies below 3 MHz, complying with IEC 60807-2.
(input/output)
(Internet control message protocol) Reports errors detected and provides information related to datagram processing.
(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 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).
(integer) A whole number encoded in 16 bits.
(Internet protocol Part of the TCP/IP protocol family that tracks the Internet addresses of devices, routes outgoing messages, and recognizes incoming messages.
Messages sent by the OPC UA server to keep a subscription active. This is necessary when none of the monitored items of data have been updated since the previous publication.
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).
(long integer) A whole number encoded in a 64-bit format (4 times INT or 2 times DINT).
(longitudinal redundancy checking) An error-detection method for determining the correctness of transmitted and stored data.
(long word) A data type encoded in a 64-bit format.
(media access control address) A unique 48-bit number associated with a specific piece of hardware. The MAC address is programmed into each network card or device when it is manufactured.
A processor task that is run through its programming software. The MAST task has 2 sections:
oIN: Inputs are copied to the IN section before execution of the MAST task.
oOUT: Outputs are copied to the OUT section after execution of the MAST task.
(management information base) An object database that is monitored by a network management system like SNMP. SNMP monitors devices are defined by their MIBs. Schneider Electric has obtained a private MIB, groupeschneider (3833).
In OPC UA, the items of data (samples) made available by the OPC UA server that clients subscribe to.
(millisecond)
(most significant bit/byte The part of a number, address, or field that is written as the left-most single value in conventional hexadecimal or binary notation.
A system of interconnected devices that share a common data path and protocol for communications.
(network management) CANopen protocols that provide services for network initialization, detected error control, and device status control.
An addressable device on a communication network.
In OPC UA, messages sent by the OPC UA server to inform clients that new items of data are available.
Open loop control refers to a motion control system with no external sensors to provide position or velocity correction signals.
See also: closed loop.
(process data object) An unconfirmed broadcast message or sent from a producer device to a consumer device in a CAN-based network. The transmit PDO from the producer device has a specific identifier that corresponds to the receive PDO of the consumer devices.
(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).
(post configuration) An option that allows to modify some parameters of the application without changing the application. Post configuration parameters are defined in a file that is stored in the controller. They are overloading the configuration parameters of the application.
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 train outputs) A fast output that oscillates between off and on in a fixed 50-50 duty cycle, producing a square wave form. PTO is especially well suited for applications such as stepper motors, frequency converters, and servo motor control, among others.
In OPC UA, the frequency at which the OPC_UA server sends notifications to clients informing them that data updates are available.
(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).
A data type that is defined as a floating-point number encoded in a 32-bit format.
A standard type of 8-pin connector for network cables defined for Ethernet.
(receive process data object) An unconfirmed broadcast message or sent from a producer device to a consumer device in a CAN-based network. The transmit PDO from the producer device has a specific identifier that corresponds to the receive PDO of the consumer devices.
(requested packet interval) The time period between cyclic data exchanges requested by the scanner. EtherNet/IP devices publish data at the rate specified by the RPI assigned to them by the scanner, and they receive message requests from the scanner with a period equal to RPI.
(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.
In OPC UA, the frequency at which the OPC UA server reads items of data from connected devices.
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
(service data object) A message used by the field bus master to access (read/write) the object directories of network nodes in CAN-based networks. SDO types include service SDOs (SSDOs) and client SDOs (CSDOs).
(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.)
(signed integer) A 15-bit value plus sign.
(simple network management protocol) A protocol that can control a network remotely by polling the devices for their status and viewing information related to data transmission. You can also use it to manage software and databases remotely. The protocol also permits active management tasks, such as modifying and applying a new configuration.
(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 variable that is a series of ASCII characters.
A group of sections and subroutines, executed cyclically or periodically for the MAST task or periodically for the FAST task.
A task possesses a level of priority and is linked to inputs and outputs of the controller. These I/O are refreshed in relation to the task.
A 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.
(transmit process data object) An unconfirmed broadcast message or sent from a producer device to a consumer device in a CAN-based network. The transmit PDO from the producer device has a specific identifier that corresponds to the receive PDO of the consumer devices.
(unsigned double integer) Encoded in 32 bits.
(user datagram protocol) A connectionless mode protocol (defined by IETF RFC 768) in which messages are delivered in a datagram (data telegram) to a destination computer on an IP network. The UDP protocol is typically bundled with the Internet protocol. UDP/IP messages do not expect a response, and are therefore ideal for applications in which dropped packets do not require retransmission (such as streaming video and networks that demand real-time performance).
(unsigned integer) Encoded in 16 bits.
A memory unit that is addressed and modified by a program.
A watchdog is a special timer used to ensure that programs do not overrun their allocated scan time. The watchdog timer is usually set to a higher value than the scan time and reset to 0 at the end of each scan cycle. If the watchdog timer reaches the preset value, for example, because the program is caught in an endless loop, an error is declared and the program stopped.
A type encoded in a 16-bit format.
