802IEEE standard that defines the Ethernet system.
Access pointJunction between a wired and wireless network.
Acyclic communicationOn-demand communications that are not scheduled.
AlarmMessage of a device event.
Alarm AckAcknowledgement from the alarm recipient on the user side.
APDU StatusApplication Protocol Data Unit Status - Contains status information regarding the transmitted cyclic user data
APIApplication Interface - A set of routines, protocols, and tools that define how software components interact.
Application readyService that the device uses to signal to the IO controller that it has entered into the operation phase, also called CControl.
ARApplication Relationship - PROFINET structure that contains communication relationships. The types of ARs are IO supervisor (IOS), IO controller (IOC), IO device (IOD) and Implicit relationship.
AR BlockPROFINET structure that contains communication relationships.
ARPAddress Resolution Protocol - The process used to find the MAC address associated with an IP address.
ASICApplication Specific Integrated Circuit – Communication chip that allows PROFINET IRT communication.
ARTAcyclic Real Time - Channel used for communication for real time alarms.
BackupOne of two Application Relationship (AR) statuses. A Backup AR carries the data that is processed by the consumer when the Primary AR is unavailable. See also “Primary.”
BroadcastAn unacknowledged transmission to a non-specified set of recipients.
CATShorthand for “Category” - Category of cables that are used for Ethernet communications. PROFINET requires cable that complies with at least CAT 5, but CAT 6 and CAT 7 cables may also be used.
CControlService that the device uses to signal to the IO controller that it has entered into the operation phase, also called Application Ready.
ChannelA single I/O point. A channel can be discrete or analog.
Client/ServerThe network node that sets up the communication connection is called a client. A server is the service provider that supplies the appropriate data at the request of a client.
COMComponent Object Model (COM)- Technology that enables software components to communicate.
Communication stackA software package used for Ethernet-based communication. It is usually divided into layers building on top of one another, thus earning the label of a "stack".
ConsumerDevice that receives data from a Provider.
CRCommunication Relationship - A virtual communication channel within an AR. The AR defines the devices and the CR is the data.
CycleInterval in which a data exchange is to take place in a periodically operating system.
Cycle CountCounter that represents the relative time from the cycle start
Cyclic communicationRepetitive communications that are scheduled to occur.
DAPDevice Access Point: A device is addressed as a single entity using this access point.
Data StatusCollection of flags that indicates whether the cyclic data is valid and can be used (also shows the status of the diagnosis and the global status of the controller).
DCOMDistributed Component Object Model - Technology for communication among software components distributed across a network.
DControlService used to signal the end of the parameterization phase to a device during system startup. It may also be referred to as “Parameter End.”
DCPDiscovery and Configuration Protocol - Protocol used for setting name and IP address for PROFINET devices.
DCSDistributed Control System- computerized control system for a process or plant, where controllers may be distributed throughout the system, but there is central operator supervisory control.
Dest AddrDestination Address - Destination of a message.
DeviceIDDevice identification for PROFINET. A manufacturer defined key unique to a specific device. The DeviceID is used in the GSDML file to allow the choosing of a specific device.
DHCPDynamic Host Configuration Protocol - Ethernet protocol that can be used to assign IP addresses. DHCP is not usually used in PROFINET. PROFINET normally relies on “static” and not “dynamic” IP addressing.
Diagnosis AlarmAlarm used to signal that an event has occurred within an IO device or in its connection to the outside world.
DL layerData Link layer, also known as Layer 2. PROFINET uses Ethernet, which is standardized as IEEE 802.3.
DNSDomain Name Service - A system for converting alphanumeric names into numeric IP addresses. DNS servers return the IP address of the web server associated with a name.
EDDEthernet Device Driver - Provider of services to send and receive cyclic, acyclic, and non-real time (NRT) messages.
Engineering ToolApplication for configuration and programming a Device. (TIA Portal)
EtherTypeIdentification of an Ethernet frame by a 16-bit number assigned by IEEE. For example, Ethertype 0x0800(hexadecimal); the RT protocol of PROFINET uses 0x8892.
Fast StartupOptimized PROFINET system startup (typically 500 ms or less).
FirewallNetwork component that restricts connections to/from the Internet for security purposes.
FragmentPart of a data packet.
Frame IDTwo byte field in the Ethernet Frame that defines the type of PROFINET message.
FTPFile Transport Protocol.
GatewayA component that enables connectivity between two networks.
GSDGeneral Station Description - A file that contains a description of a device and its’ features. Typically associated with PROFIBUS slaves, but the term may also be used to describe PROFINET GSDML files.
GSDMLGeneral Station Description Markup Language - XML based language used to describe PROFINET device features.
HMIHuman Machine Interface - Component of a control system or process control system that is used to generate and display information from the process and to record and initiate control actions.
HTMLHypertext Markup Language - Interpreted language that defines the “look and feel” of web pages
HTTPHyperText Transfer Protocol - Communication protocol used to establish a connection with a server.
HTTPSHyperText Transfer Protocol Secure - Variant of the standard web transfer protocol (HTTP) that adds a layer of security on the data in transit through a secure socket layer (SSL) or transport layer security (TLS) protocol connection.
I&MIdentification and Maintenance - services that provide support during commissioning and maintenance.
ICMPInternet Control Message Protocol - Error reporting protocol used by network devices to generate messages to the source IP address when a network problem prevents delivery of IP packets.
IdentifyA DCP service used to request a station to identify itself.
IECInternational Electrotechnical Commission - Organization that publishes international standards for electrical technologies.
IEC 61158International Fieldbus Standard that contains PROFINET and PROFIBUS.
IO ControllerDevice that initiates IO data communication. It can be a PLC. Sometimes referred to as IOC.
IOCSIO Consumer Status - The consumer (receiver) of a cyclic I/O data element uses this to signal the status (good/bad with error location).
IO DeviceField device that performs IO transfer between the PROFINET network and the physical inputs or outputs. Sometimes called IOD.
IOPSIO Provider Status - The provider (sender) of a cyclic I/O data element uses this to signal the status (good/bad with error location).
IO Supervisor Engineering tool for commissioning and configuring PROFINET networks. May also be called IOS.
IP AddressInternet Protocol Address - Numerical label assigned to devices participating in a network.
IPAR ServerIO Parameter Server- Server station for loading and saving the configuration data of I/O devices.
IRTIsochronus Real Time - Communication channel used in PROFINET, for the deterministic transfer of data.
LANLocal Area Network - Network that connects devices that share a common communications line.
LLDPLink Layer Discovery Protocol - IP layer protocol used by devices to advertise their identity, capabilities and neighbors on an IEEE 802 Local Area Network.
MAC AddressMedia Access Control Address - Used to identify an Ethernet node. The MAC address has a length of 6 bytes and is assigned by IEEE. Sometimes referred to as Ethernet address
MCRMulticast Communication Relation - Communication channel between devices without direct involvement of the higher-level controller defined in PROFINET.
MIBManagement Information Base – SNMP (Simple Network Management Protocol) agent Database containing managed device parameters. The MIB can be queried by the SNMP manager.
MIIMedia Independent Interface - Standardized interface between the Ethernet controller and the transmission equipment.
ModulesVendor defined components that plug into slots. Modules may be physical or virtual.
MRPMedia Redundancy Protocol - Describes the ring redundancy according to IEC 61158.
MRPDMedia Redundancy for Real-Time with Planned Delay - MRP variant used for IRT communication.
MulticastTransmission to multiple destinations at the same time.
Network AddressA logical or physical address that uniquely distinguishes a network node or device on a communication network.
NDRNetwork Data Representation - 20-byte header that is needed for data representation of RPC blocks.
NRTNon Real Time - PROFINET communication channel used for all communication that is not considered Real-Time. PROFINET Channel Configuration and Diagnostic messages are transferred using the NRT channel.
OPCOLE for Process control - Process control optimized set of standards based on OLE/COM technology.
OUIOrganizationally Unique Identifier - Vendor related identification assigned by IEEE to companies. OUI is the first 3 bytes of a MAC address.
Parameter EndService used to signal the end of the parameterization phase to a device during system startup. Also known as DControl.
PDUProtocol Data Unit – Data Block that contains protocol information (SrcAdr, DstAdr, checksum and service parameter information) that is passed from a protocol instance of transparent data to a lower level (on the lower level is the information that is transferred).
PLCProgrammable Logic Controller - Computer used for automation of industrial electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or light fixtures.
Plug AlarmAn alarm that is triggered when a module is inserted into a rack. Module parameters may be downloaded with the plug alarm.
Port MAC AddressMAC address of a specific port of a PROFINET switch. A particular port is identified using a Port MAC address (PMA). PROFINET transmits some frames based on the PMA so that switches do not have to change addresses or relearn partners in redundant operation.
PNO/PIPROFIBUS Nutzerorganisation e. V. - PROFIBUS & PROFINET International (PI) - the International organization responsible for PROFIBUS and PROFINET technologies.
PrimaryApplication relationship (AR) that carries the data that is processed by the consumer. See also “Backup.”
Priority TaggingLayer 2 Priority field that is inserted in an Ethernet frame according to IEEE 802.1p. PROFINET uses Priority level 6.
Process AlarmAlarm used to signal an event that has occurred external to the device, (e.g. overpressure in a boiler.)
ProfilePROFINET International defined set of functionalities and services a device has to deliver and perform. Some common Profiles are PROFISAFE, PROFIENERGY, and PROFIDRIVE.
Profile IDA PROFINET defined entity that is used in combination with an API to uniquely identify the access and behavior of an application (e.g. PROFIdrive, Encoder, PROFIEnergy etc.)
PROFINETThe Open Industrial Ethernet Standard defined by PROFIBUS and PROFINET International.
ProviderAn entity that sends data to consumers in the form of messages.
ProxyIn PROFINET, a proxy is a concept to integrate a fieldbus network into a PROFINET network. In effect the proxy is a translator. On the fieldbus side it is the Controller of the network, and in the PROFINET network it acts as a PROFINET I/O device, transferring data between the two networks.
PTCPsyncPrecision Transparent Clock Protocol - Procedure for precise time synchronization. Used for IRT. It is defined in IEC 61158.
PTCP MasterTime generator for PTCP in an IRT domain.
PTCP SlaveStation that is synchronized by a PTCP master
Pull AlarmAn Alarm that is triggered when a module is removed from the rack.
RARPReverse Address Resolution Protocol - Identifies the IP address associated with a MAC address. RARP is defined in RFC 903.
Real-TimeThe capability of a system to complete a task in a pre-defined amount of time. The term is
Record DataStructured data that are provided for acyclic access within a field device.
Redundancy AlarmAlarm that is triggered when the status of the associated redundancy AR changes.
REQ(uest)Data unit of the transmission from sender/client to receiver/server.
RES(ponse)Data unit of the transmission from server to client.
Return AlarmAlarm that indicates that an IO element is in data exchange again.
RPCRemote Procedure Call - PROFINET uses Open Software Foundation (OSF): C706, CAE Specification DCE11 Remote Procedure Call.
RSTPRapid Spanning Tree Protocol - Protocol that prevents packets from circulating between switches in a mesh or ring topology; RSTP is specified in IEEE 802.1 D (issue 2004).
RTReal-Time - Designation of a real-time protocol that can be operated without special support in Ethernet controllers. The RT protocol is typically used when IRT is not available.
RTAReal-Time Acyclic protocol - Used for transferring alarm information.
RTA AckAcknowledgement of the RT Acyclic protocol RT Frames Messages that use EtherType 0x8892.
SlotSlot is an organizational grouping in the PROFINET device model. A PROFINET device consists of one or more slots. Slots may be physical or virtual. Slots can be thought of as plug-in modules that define the specific way the device is to function. (e.g. an 8 point discrete output module.) Slots are made up of Subslots.
SNMPSimple Network Management Protocol - SNMP is the standard Internet protocol for management and diagnosis of network components (see also RFC 1157 or RFC 1156 at
SRC AddrSource address - Address of the originator of a message
STPShielded, Twisted, Pair - a method of manufacturing cables that reduces common-mode interference. STP is used in Cat 5 and other types of Ethernet cables.
Subnet Subnetwork - a logical subdivision of an IP network.
Subnet MaskA 32 bit mask used for routing traffic within a subnet. It divides the IP address into two parts, a host address and a network address.
SubslotA grouping of one or more channels. Subslots may be physical or virtual.
Sync DomainSync Domain - consists of a Sync Master and at least one Sync slave. All PROFINET devices that are to be synchronized with IRT must belong to a Sync Domain.
TCITool Calling Interface - Specifies an open interface for integrating Device Tools in an engineering system.
TCP/IPTransport Control Protocol / Internet Protocol-Two protocols used across ISO layers 3 and 4 to provide message routing, error detection and correction, message acknowledgement, retransmission, and windowing services.
TopologyPhysical layout of network devices. Common topologies include lines, rings, trees and meshes.
UDPUser Datagram Protocol - Routable ISO layer 4 protocol defined in RFC 768.
UUIDUniversal Unique Identifier – Identifier used by COM to identify an object and interfaces. Controls the unique identification of a particular functionality in PROFINET.
Vendor IDThe PNO assigned manufacturer specific identification. PROFINET device manufacturers can be identified by the Vendor ID accessible through the I&M PROFINET information.
VLANVirtual Local Area Network - Group of one or more devices or one or more LANs that are configured to communicate as if they were attached to a common wire.
WANWide Area Network- a communications network that extends over a large geographical distance.
XMLeXtensible Markup Language- a markup language that defines a set of rules for encoding information that is both human-readable and machine-readable.
XML ParserProgram for checking XML files against schemas.

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