An adapter is the target of real-time I/O data connection requests from scanners. It cannot send or receive real-time I/O data unless it is configured to do so by a scanner, and it does not store or originate the data communications parameters necessary to establish the connection. An adapter accepts explicit message requests (connected and unconnected) from other devices.

In Control Expert, Advanced mode is a selection that displays expert-level configuration properties that help define Ethernet connections. Because these properties are designed to be edited only by persons with a solid understanding of communication protocols, they can be hidden or displayed, depending upon the qualifications of the specific user.

(bootstrap protocol) A UDP network protocol that can be used by a network client to automatically obtain an IP address from a server. The client identifies itself to the server using its MAC address. The server—which maintains a pre-configured table of client device MAC addresses and associated IP addresses—sends the client its defined IP address. The BOOTP service utilizes UDP ports 67 and 68.

A message sent to all devices in the subnet.

(Common Industrial Protocol) A comprehensive suite of messages and services for the collection of manufacturing automation applications—control, safety, synchronization, motion, configuration and information. CIP allows users to integrate these manufacturing applications with enterprise-level Ethernet networks and the Internet. CIP is the core protocol of EtherNet/IP.

A CIP transport class 1 connection used for I/O data transmission via Implicit Messaging between EtherNet/IP devices.

A CIP transport class 3 connection used for Explicit Messaging between EtherNet/IP devices.

In EtherNet/IP, connected messaging uses a CIP connection for communication. A connected message is a relationship between two or more application objects on different nodes. The connection establishes a virtual circuit in advance for a particular purpose, such as frequent explicit messages or real-time I/O data transfers.

A virtual circuit between two or more network devices, created prior to the transmission of data. After a connection is established, a series of data is transmitted over the same communication path, without the need to include routing information—including source and destination address—with each piece of data.

The EtherNet/IP network node that initiates a connection request for I/O data transfer or explicit messaging.

Describes communication between two network devices, whereby data is sent without prior arrangement between the two devices. Each piece of transmitted data also includes routing information—including source and destination address.

See producer/consumer, below.

(carrier sense multiple access with collision detection) An Ethernet and IEEE 802.3 media access method, operating at the physical layer and handled fully by hardware at the communication media signal level. All network devices contend equally for access to transmit. When a device (device ‘A’) detects a signal sent by another device (device ‘B’) while A is transmitting, A aborts its transmission and retries after a random period of time.

(dynamic host configuration protocol) An extension of the BOOTP communications protocol that provides for the automatic assignment of IP addressing settings—including IP address, subnet mask, gateway IP address, and DNS server names. DHCP does not require the maintenance of a table identifying each network device. The client identifies itself to the DHCP server using either its MAC address, or a uniquely assigned device identifier. The DHCP service utilizes UDP ports 67 and 68.

(domain name server/service) A service that translates an alpha-numeric domain name into an IP address, the unique identifier of a device on the network.

An alpha-numeric string that identifies a device on the internet, and which appears as the primary component of a web site’s Uniform Resource Locator (URL). For example, the domain name "schneider-electric.com" is the primary component of the URL "www.schneider-electric.com".

Each domain name is assigned as part of the Domain Name System, and is associated with an IP address.

Also called a host name.

(device type manager) A DTM is a device driver running on the host PC. It provides a unified structure for accessing device parameters, configuring and operating the devices, and diagnosing events. 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. In the context of a DTM, a device can be a communications module or a remote device on the network.

(electronic data sheet) EDS are simple text files that describe the configuration capabilities of a device. EDS files are generated and maintained by the manufacturer of the device.

A 10 or 100 Mb/s, CSMA/CD, frame-based LAN that can run over twisted pair or fiber optic cable, or wireless. The IEEE standard 802.3 defines the rules for configuring a wired Ethernet network; the IEEE standard 802.11 defines the rules for configuring a wireless Ethernet network.

A network communication protocol for industrial automation applications that combines the standard internet transmission protocols of TCP/IP and UDP with the application layer Common Industrial Protocol (CIP) to support both high speed data exchange and industrial control. EtherNet/IP employs electronic data sheets (EDS) to classify each network device and its functionality. Because EtherNet/IP is based on standard Ethernet protocols, it can be implemented using commercially available Ethernet components and cabling.

TCP/IP-based messaging for Modbus TCP and EtherNet/IP. It is used for point-to-point, client/server messages that include both data—typically unscheduled information between a client and a server—and routing information. In EtherNet/IP, Explicit Messaging is considered Class 3 type messaging, and can be connection-based or connectionless.

Explicit Messaging client class) Device class defined by the ODVA for EtherNet/IP nodes that only support Explicit Messaging as a client. HMI and SCADA systems are the most common examples of this device class.

The ability of a two networked devices to independently and simultaneously communicate with each other in both directions.

A device that interconnects two different networks—sometimes with different network protocols. When used to connect networks based on different protocols, a gateway converts a datagram from one protocol stack into the other. When used to connect two IP-based networks, a gateway (also called a router) has two separate IP addresses - one on each network.

A multiport device used to span longer network distances by connecting several Ethernet devices with shielded/unshielded twisted pair or fiber optic cables. Messages received by a hub are repeated on all ports. All connected devices are part of the same segment, share bandwidth and operate via half-duplex communication. A hub lacks the ability to filter network messages based on their source and destination address. Because communication is half-duplex, the likelihood of collisions is increased. Collisions are handled by each connected device using CSMA/CD. Hubs are OSI Layer 1 (physical layer) devices.

UDP/IP-based class 1 connected messaging for EtherNet/IP. Implicit messaging maintains an open connection for the scheduled transfer of control data between a producer and consumer. Because an open connection is maintained, each message contains primarily data—without the overhead of object information—plus a connection identifier.

The 32-bit identifier—consisting of both a network address and a host address—assigned to a device connected to a TCP/IP network.

Functionality offered by Schneider Electric EtherNet/IP communication modules that allows a Scanner to take the role of an Adapter. The local slave enables the module to publish data via Implicit Messaging connections. Local slave is typically used in peer-to-peer exchanges between PLCs.

A special form of broadcast where copies of the packet are delivered to only a subset of all possible destinations. Implicit Messaging typically uses multicast format for communications in an EtherNet/IP network.

Originator to target.

In EtherNet/IP a device is considered the originator when it initiates a CIP connection for Implicit or Explicit Messaging communications; or when it initiates a message request for un-connected Explicit Messaging.

CIP, the core protocol for EtherNet/IP, uses the producer/consumer model, as opposed to the client/server message addressing scheme employed by Modbus TCP. The producer/consumer model is inherently multicast. Nodes on the network determine if they should consume the data in a message based on the connection ID in the packet.

Quality of Service The practice of assigning different priorities to traffic types for the purpose of regulating data flow on the network. In an Industrial network, QoS can help provide a predictable level of network performance.

Data from multiple I/O modules are consolidated in a single data packet to be presented to the Scanner in an Implicit Message in an EtherNet/IP network.

(requested packet interval) The time period between cyclic data transmissions requested by the Scanner. EtherNet/IP devices will publish data at the rate specified by the RPI assigned to them by the Scanner. Modbus TCP devices will receive message requests from the Scanner at each RPI.

A Scanner acts as the originator of I/O connection requests for Implicit Messaging in EtherNet/IP, and message requests for Modbus TCP.

A Scanner Class device is defined by the ODVA as an EtherNet/IP node capable of originating exchanges of I/O with other nodes in the network.

The 32-bit value used to hide (or mask) the network portion of the IP address and thereby reveal the host address of a device on a network using the IP protocol.

A multiport device used to segment the network and limit the likelihood of collisions. Packets are filtered or forwarded based upon their source and destination addresses. Switches are capable of full-duplex operation and provide full network bandwidth to each port. A switch can have different input/output speeds (for example, 10, 100 or 1000Mbps). Switches are considered OSI layer 2 (data link layer) devices.

Target to originator.

In EtherNet/IP a device is considered the target when it is the recipient of a connection request for Implicit or Explicit Messaging communications; or when it is the recipient of a message request for un-connected Explicit Messaging.

(transmission control protocol) TCP is the OSI transport layer protocol that supports connection-oriented communications, by establishing the connection necessary to transmit an ordered sequence of data over the same communication path.

Also known as "Internet protocol suite", TCP/IP is a collection of protocols used to conduct transactions on a network. The suite takes its name from the two most broadly used protocols: transmission control protocol and internet protocol. TCP/IP is a connection-oriented protocol that is used by Modbus TCP and EtherNet/IP for Explicit Messaging.

A trap is an event directed by an SNMP agent that indicates either:

(user datagram protocol) UDP is a transport layer protocol that supports connectionless communications. Applications running on networked nodes can use UDP to send datagrams to one another. Unlike TCP, UDP does not attempt to provide deterministic delivery or ordering of datagrams. However, by avoiding the overhead required by deterministic delivery and checking of datagrams, UDP is faster than TCP. UDP may be the preferred protocol for time-sensitive applications, where dropped datagrams are preferable to delayed datagrams. UDP is the primary transport for Implicit Messaging in EtherNet/IP.

In EtherNet/IP, unconnected messaging uses TCP (without a CIP connection) to send explicit messages. More overhead is contained within each unconnected message than for a connected message. The unconnected message is not necessarily provided destination node resources. Unconnected Messaging is used for non-periodic requests.