Industrial communication glossary
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 1
Appendices Appendices
What do these designations mean? ð "SensorBus" (sensor/actuator bus) : this is a totally deterministic bus with very short response times. It is not necessary to inform higher levels with the same response times. AS-i, Bitbus, and Seriplex are all examples of the SensorBus. ð "DeviceBus" (control system peripheral bus) : autonomous operations and reflex control systems predominate with the DeviceBus. The DeviceBus is oriented towards high-speed manufacturers and deterministic systems. DeviceNet, Device WorldFIP (DWF), SDS, Interbus and Profibus DP are all examples of the DeviceBus. ð "FieldBus" (bus linking processing units) : the FieldBus is positioned between processing units as a synchronization bus. The FieldBus is oriented towards low-speed, continuous processes. Profibus FMS, Profibus PA, FieldBus WorldFIP, FieldBus Foundation and Modbus + are all examples of the FieldBus. ð "DataBus" (data-carrying bus) : used in the majority of cases to transfer and configure files on computer networks. MMS on Ethernet, FDDI and MAP are the some of the best known examples of the Databus.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 2
AS-i AS-i GLOSSARY GLOSSARY
Addressing terminal
: standalone casing for assigning an address to an AS-i slave
AS-i
: Actuator Sensor Interface
AS-i cable
: 2-wire unshielded flat cable with lip or round cable
Asi-ed sensor
: sensor integrating AS-i chip for connection to tap links or passive splitters.
AS-i master
: PLC coupler or PC or gateway or special casing for managing the AS-i bus
AS-i power supply unit
: supplies power to the AS-i bus and some sensors/actuators
AS-i slave
: AS-i bus element (bus, sensor or actuator interface) integrating an AS-i chip
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 3
AS-i AS-i GLOSSARY GLOSSARY
Active slave
:
projected slave which has been recognized
Active splitter
:
box for connecting 4 standard components. User module and connection module are linked
Active user module
:
upper part (integrating the AS-i chip) of a splitter for connecting standard sensors
Auxiliary power supply unit
:
powers sensors/actuators externally to the AS-i bus
Connection module
:
box for connecting AS-i flat cable(s) or a round cable (lower part of a splitter)
Detected slave
:
slave connected on the bus
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 4
AS-i AS-i GLOSSARY GLOSSARY Gateway
: combined hardware and software providing an interface between the AS-i bus and another network
Passive splitter
: box for connecting 4 AS-i sensors/actuators. User module and connection module are linked
Passive user module : upper part (not integrating the AS-i chip) of a splitter for connecting Asi-ed sensors Projected slave
: slaves projected during the bus configuration
Tap link
: low-cost solution for connecting the AS-i bus flat cable to the sensor/actuator round cable via M12 connector
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 5
GENERAL GENERAL GLOSSARY GLOSSARY
Access time The time between launching a find operation and obtaining the information. Address Unique binary sequence, character or group of characters identifying a network station, a user or an application; unique description for data location; used especially for routing. Attenuation Where signals are weakened by the length of the cable and the number of junctions (fiber). Amplitude Physical size characterizing a wave signal which represents the extreme (peak) signal values; by extension, the signal value at a given moment (instantaneous amplitude). Amplitude modulation Modulation process varying the amplitude of a carrier as a function of the signal applied to it.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 6
GENERAL GENERAL GLOSSARY GLOSSARY
Amplitude transfer modulation Amplitude modulation technique based on transitions between distinct levels (in general two levels). Application Programs performing operations used for processing or manipulating data, including database managers, word processors, spreadsheets and other programs capable of producing useful data. ASCII A system of binary code which defines 128 characters in combinations of 1 and 0. ASCII = American Standard Code for Information Interchange. Asynchronous Transmissions where the terminals are not in phase (see asynchronous transmission). Attenuation Damping or reduction. Reduction of the signal amplitude.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 7
GENERAL GENERAL GLOSSARY GLOSSARY
Bandwidth Band of frequencies supported by a system with little or no loss. The difference between the lowest and highest frequencies on which a link can pass correctly; it determines the maximum channel traffic capacity. Baud Unit of modulation speed. Bit A bit is a binary digit, 1 or 0. Bit/s Data transmission is expresses in the number of bits/s. See baud. bps (bits per second) Elementary unit for measuring the serial data transmission rate; kbps for kilobits per second (one thousand bps); Mbps for megabits per second (one million bps); Gbps for gigabits per second (one billion bps); Tbps for terabits per second (one trillion bps).
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 8
GENERAL GENERAL GLOSSARY GLOSSARY
Bridge Interconnection between two local networks at the link layer (level 2 of the ISO model). To be distinguished from gateways. Buffer Buffer, spooler. Memory which can store data temporarily while (for example) waiting until the receiver is ready; used to compensate for differences in data transfer rates between two devices (adaptation). Bus Transmission path or channel; electrical connection of one or more conductors, by means of which all connected devices simultaneously receive all data. The wiring of the local network has a linear topology such as Ethernet on a coaxial cable or the "Token Bus", where all nodes in the network "listen" for all transmissions and identify those which contain their address. Byte Unit of data especially used for parallel transmissions; the capacity of a semi-conductor or of a memory (usually as a group of 8 bits). Often called a "character": it consists of binary numbers. An ASCII character consists of 7 to 8 bits and corresponds to an alphanumeric character.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 9
GENERAL GENERAL GLOSSARY GLOSSARY Carrier Continuous signal of a determined frequency which is modulated for use in data transmission. Channel Media used for transmission of signals on a line of communication. Client/Server Concept by means of which an application is shared between a server which makes resources or services available to a client, which manages the graphical interface. Clock A regular frequency sent by a source (clock generator), used especially for controlling data flows in serial transmissions. Coaxial Asymmetrical pair consisting of a central conductor (core) and a concentric external conductor (braid); characterized by its low attenuation, its bandwidth and its high immunity to external interference.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 10
GENERAL GENERAL GLOSSARY GLOSSARY Collision Occurs when two stations send simultaneously on a CSMA/CD network. The result is the loss of the data sent. Concentrator Device for concentrating traffic. It may be intelligent enough to manage various switching operations and protocols. Connection Logical link between two entities. Connection time Period a communication line/circuit is busy. Control character Control character calculated on the length of a data block in accordance with a checking algorithm and then added to the end of the block.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 11
GENERAL GENERAL GLOSSARY GLOSSARY CRC (Cyclic Redundancy Check) Technique for detecting errors where the block control character (the CRC) is calculated via polynomial division and added to the end of each block. CSMA/CD (Carrier Sense Multiple Access with Collision Detection) Method of accessing local networks where access is allocated by listening to the line and detecting the collision : if several stations transmit simultaneously, a collision signal is transmitted; each station attempts to re-send the packet a limited number of times after a random period of a few microseconds. Current loop Serial transmission method which transforms signals into a current or absence of current on the wire pair. Dead time Time a transmission line is unavailable. DIN rail Standard means of mounting devices in cabinets.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 12
GENERAL GENERAL GLOSSARY GLOSSARY Distributed system System where a certain number of processors at different locations perform operations which are specific to their environment as well as communication functions. Duplex Communication in two directions. In half-duplex, transmission and reception are alternating; in full duplex, they are simultaneous. Dynamic routing Process which directs messages across the network. When a path is deactivated or overloaded, an alternative route (secondary) is automatically selected. This method is used on packet switching networks (X25 for example). Fiber optics Any filament or fiber made of dielectric material for transmitting laser light signals or signals generated by light-emitting diode (LED); an optical fiber generally consists of : -a core to transport the signal, -a cover with a slightly higher refractive index, which surrounds the core and reflects the light signal.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 13
GENERAL GENERAL GLOSSARY GLOSSARY Flow control Technique which involves controlling the transfer of data between two points on a network. Frame Data block in a link protocol. Frequency modulation Modulation imposed on the carrier frequency as a function of the amplitude of the signal to be transmitted. Frequency multiplexing Multiplexing based on the use of a bandwidth for each signal by dividing the available bandwidth. Frequency transfer modulation Technique for modulating the frequency where each of the two binary states, 0 and 1, is associated with a determined frequency. Gateway Software (sometimes hardware) interface used for communication between two networks which have different protocols and/or physical media.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 14
GENERAL GENERAL GLOSSARY GLOSSARY IEEE (Institute of Electrical and Electronic Engineers) International professional body, member of the ISO and the ANSI, which produces standards. IEEE 802 Draft for the standardization of local networks produced by an IEEE working party. IEEE 802.2 Data Link Layer standard used in IEEE 802.3, 802.4, 802.5. IEEE 802.3 Physical link standard using the CSMA/CD access method and bus topology (similar to Ethernet). IEEE 802.4 Physical link standard using the token passing access method on a bus topology network. Almost identical to MAP. IEEE 802.5 Physical link standard using the token passing access method on a ring network architecture.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 15
GENERAL GENERAL GLOSSARY GLOSSARY Impedance Effect of the capacity of an electrical circuit linked to the transmission of a signal. The relationship between the voltage and the intensity of an alternating current at the ends of a device, expressed in a complex form where the whole represents the resistance and the notional part is the reactance. Interconnection The physical and data connections linking various communication systems to each other. Interface A piece of hardware or software used for communication between two physical or data entities. Internet Network consisting of a number of smaller networks which use the TCP/IP protocol. Inter-network router Device used to interconnect networks. Only transmits messages to one of the sub-networks if the subnetwork is the destination. Functions at level 3 (network) of the OSI model. Interrogation The main computer asks connected devices if they have any data for transmission.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 16
GENERAL GENERAL GLOSSARY GLOSSARY ISA Internal architecture of the data bus in IBM PCs, AT. Layer In a local network, the range of network management functions corresponding to one of the hierarchical levels of the OSI model. LCD (Liquid Crystal Display) Screen which uses liquid crystals. Local area network (LAN) Installation of high-capacity communication media (coaxial cable, twisted pair or optical fiber) under the control of a common operating system on the same delimited site (campus or building). A local business network. Line terminator Resistor located at the end of a transmission line, with a value equal to the characteristic impedance, designed to prevent reflections or stationary waves when a signal is sent from the other end of the line.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 17
GENERAL GENERAL GLOSSARY GLOSSARY LLC (Logical Link Control) Protocol developed by the IEEE 802.2 committee for checking transmissions at link level; the upper part of sub-layer 2 of the ISO model which completes the MAC protocol; includes final addressing and error correction. Mb (Megabyte) 1,048,573 octets, or 1,024 kilobytes; the unit of measurement for data storage, also used for measuring the speed of data transfers (Mb/s). Modem Modulator/demodulator; DCE converting D/A and A/D signals between DTEs and an analog data transmission network. Modulation Modification the characteristic (frequency, phase, amplitude) of a carrier as a function of the signal variations (modulation signal). Multi-drop Simultaneous connection to several points.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 18
GENERAL GENERAL GLOSSARY GLOSSARY Multimode Technique for transmitting via optical fiber where the beams are reflected in the core. Multiplexer Device used to manage several simultaneous low-speed channels on a high-speed channel. Multiplexing Dividing a transmission line into sub-channels, each carrying an independent signal. Network General description of communication links between two or more devices. Network Management Set of functions/processes employed in control of network operations including configuration, diagnostics, user statistics and traffic monitoring functions, fault detection and measurement of operating costs. Node Connection point for one or more devices on a communication line, device for transmitting on a network; includes communication processors, terminal controllers, cluster controllers and terminals.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 19
GENERAL GENERAL GLOSSARY GLOSSARY Operating system Computer software specifically for checking execution of programs, management of I/O, allocation of resources and data management (e.g. MS-DOS®). Optocoupler Used for transmitting signals via light beams : examples are light emitting diodes and phototransistors. An optocoupler does not conduct any electrical current and thus ensures electrical isolation. OSI (Open System Interconnection) A reference model for defining data handling in the various communication layers. Packet Message unit for a packet switching network; contains the data block and the identification information required for transmission. Parallel interface Interface used for simultaneous transmission of a group of bits by sending each bit on a different channel.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 20
GENERAL GENERAL GLOSSARY GLOSSARY Parallel transmission Simultaneous transmission of bits via several conductors. An 8-bit character (= 1 byte) requires 8 parallel conductors. 32-bit communication transmits 4 bytes simultaneously on 32 parallel conductors. This type of transmission is mainly used inside computers and over very short distances. Parity bit Check bit calculated and added by the sending device. A receiving unit checks the parity and can thus detect transmission errors. Passing token Access method where a token passes from station to station to enable data transmission. Each station can add a message in turn for circulation on the network. All stations "see" the message as it passes, but only the destination station accepts it. Phase modulation Assigns the signal position during the period (the phase angle) for coding bits. Used mainly in digital transmission. PLC Programmable logic controller.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 21
GENERAL GENERAL GLOSSARY GLOSSARY Polling Invitation to send; process of interrogating terminals of a multi-drop link via computer in a predetermined order in order to respond to a transmission request. Protocol Set of rules/procedures/conventions used to formulate data transfer standards; communication rules between computer entities at the same level. PVC Plastic insulating material widely used in cable manufacturing. Redundancy check (See CRC); technique for detecting errors by adding additional control bits. The CRC is a control character for a particular block. It is added to the end of each block. Repeater Active device for amplifying, resynchronizing and relaying data (frames) circulating between two cable segments on the same network; an optical fiber repeater decodes low power optical signals, converts them into electrical form and passes them through a LED or laser source. Also called "regenerator repeater".
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 22
GENERAL GENERAL GLOSSARY GLOSSARY Response time Reaction time when a system is prompted. Resource allocations Sharing of system resources between several users. Resources All devices, data and applications which can be used by one or more users on a computing site. Ring Closed loop network topology; different from bus or star networks. Ring network A network in series in which all units form a closed ring and all transmissions pass through all units. Router Gateway for interconnecting two networks : it switches on an address at network level. Routing Determination of the data paths through the network nodes.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 23
GENERAL GENERAL GLOSSARY GLOSSARY
Segment Delimited part of a network. Star network A network where the central unit is directly connected to the peripherals. Semaphore In terms of local networks, a reservation message transmitted when a user accesses a disk or a file to prohibit access to other users. Serial transmission Transmission of one character at a time on one conductor, as opposed to parallel transmission. Shared architecture Local network using a common communication support, in bus or star topology, with shared access. Simplex Communication in one direction only.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 24
GENERAL GENERAL GLOSSARY GLOSSARY Single mode Technique for transmitting optical signals via cable. Used most frequently for transmitting laser beams along very thin cores (singlemode optical fiber). Star Network topology where all stations are individually connected to a central point. Star network Star topology. Network topology where the stations are connected to a central node which performs the required switching functions. Start bit Signals the start of a transmission. In asynchronous transmission, each character begins with a start bit. Status signal Indicates the status of connected units : run, ready to receive, ready to send, paper jam, etc. Stop bit One or more stop bits signaling that the character is finished.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 25
GENERAL GENERAL GLOSSARY GLOSSARY Synchronous transmission The characters are sent and received in sequence at a constant speed. The timing is managed by clock signals. Time multiplexing Procedure for dividing the transmission time of a high-capacity line into intervals which can be allocated to lines with a lower capacity. Token Packet or portion of a packet circulating on a network with explicit access. The token "belongs" to the station controlling the transmission medium. Token ring Ring-shaped network on which a packet is presented sequentially to each station; a header bit indicates that it contains a message (in which case the send and receive addresses are present). Topology Configuration of a network. Geometrical or logical structure of a network. For example : token ring, star, mesh, etc.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 26
GENERAL GENERAL GLOSSARY GLOSSARY
Twisted pair A transmission line consisting of two insulated conductors twisted together to produce a characteristic impedance which is constant along the entire line; typically used for telephone cables, twisted unshielded pairs have no shielding braid or screen. Wavelength Distance between two successive peaks in the amplitude of a wave. Wide band A technique used for simultaneous transmission of several data, sound and image channels at different frequencies.
Industrial Automation - Customer View - Training PhW - Com_glossary_en - 02 / 2002
Diapositive 27
