According to the IEC standard, %I indicates a discrete input-type language object.

According to the IEC standard, %IW indicates an analog input-type language object.

According to the IEC standard, %M indicates a memory bit-type language object.

According to the IEC standard, %MW indicates a memory word-type language object.

According to the IEC standard, %Q indicates a discrete output-type language object.

According to the IEC standard, %QW indicates an analog output-type language object.

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.

A module that contains circuits that convert analog input signals to digital values that can be manipulated by the processor. By implication, these analog inputs are usually direct. That means a data table value directly reflects the analog signal value.

A module that contains circuits that transmit an analog signal proportional to a digital value input to the module from the processor. By implication, these analog outputs are usually direct. That means a data table value directly controls the analog signal value.

A software application that can configure, monitor, and manage devices employed as part of an industrial automation system.

Communication mode typified by the absence of a global, fixed-rate clock signal. Instead, asynchronous communication control is spread among multiple devices, that communicate and synchronize over shared channels.

The automatic assignment of an address to each island bus I/O module.

The ability of island modules to operate with predefined default parameters. A configuration of the island bus based completely on the actual assembly of I/O modules.

A standard defining the operation of frequency shift keying: a frequency modulation scheme that transmits digital information by means of discrete frequency changes in a carrier wave.

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.

(change configuration on the fly) A feature of Control Expert that allows a PLC hardware change in the system configuration while the PLC is operating and not impacting other active drop operations.

(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 connection used for I/O data transmission via implicit messaging between EtherNet/IP devices.

A CIP transport connection used for explicit messaging between EtherNet/IP devices.

The arrangement and interconnection of hardware components within a system, and the hardware and software settings that determine the operating characteristics of the system.

An analog electrical signaling scheme, that allows a device to be monitored or controlled over a pair of conductors. Only one current level can exist in a current loop at any point in time. A digital signal can be added to the analog current loop using the HART protocol, enabling additional communication with the analog device.

Device Description Language file: A definitional template for a HART field instrument, that describes its configurable parameters, the data that it can produce, and its operating procedures, including menus, commands and display formats.

(derived data type) A set of elements with the same type (array) or with different types (structure).

A user-defined, unique identifier for an Ethernet device. After the device is configured with a valid device name, a DHCP server can use it to identify the device and provide it with an IP address at power up.

(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.

Deutsche Industrial Norms. A German agency that sets engineering and dimensional standards and now has worldwide recognition.

(device type manager) A device driver running on the host PC. It provides a unified structure for accessing device parameters, configuring and operating the devices, and troubleshooting the network. DTMs can range from a simple graphical user interface (GUI) 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.

See FDT.

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

Electronic Industries Association: An organization that establishes electrical/electronic and data communication standards.

electromagnetic compatibility: Devices that meet EMC requirements can operate within a system’s expected electromagnetic limits without interruption.

electromagnetic interference: EMI can cause an interruption or disturbance in the performance of electronic equipment. It occurs when a source electronically transmits a signal that interferes with other equipment. Also known as radio frequency interference (RFI).

A 10 Mb/s, 100 Mb/s, or 1 Gb/s, CSMA/CD, frame-based LAN that can run over copper 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. Common forms include 10BASE-T, 100BASE-TX, and 1000BASE-T, which can utilize category 5e copper twisted pair cables and RJ45 modular connectors.

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.

A known state to which an output module can return in the event that it loses communication with the PLC.

(fast device replacement) A service that uses configuration software to replace an inoperable device.

functional ground: A grounded supply conductor, often carrying current, that is used to enhance the operation of equipment. Contrast: protective ground (PE).

Nonvolatile memory that can be overwritten. It is stored on an EEPROM that can be erased and reprogrammed.

(file transfer protocol) A protocol that copies a file from one host to another over a TCP/IP-based network, such as the internet. FTP uses a client-server architecture as well as separate control and data connections between the client and server.

The ability of 2 networked devices to independently and simultaneously communicate with each other in both directions.

A system of communication between 2 networked devices that provides for transmissions in both directions, but in only one direction at a time.

Highway Addressable Remote Transducer protocol: A bi-directional communication protocol for transmitting—across analog wires—digital information between intelligent field devices and a host control/monitoring system. For more information, refer to the HART Communication Foundation web site: www.hartcomm.org.

A modem that serves as the pass through device between one or more HART master devices, and multiple HART slave devices.

A HART host application, typically resident in a PC. For example, asset management software.

A HART compliant smart field device, which responds via the HART protocol only when commanded to do so by a HART master.

A frequency-based filter that permits transmissions only above a pre-set frequency threshold to pass. In HART, the frequency threshold is typically set in range of 400...800 Hz: transmissions above this threshold—HART digital signals—are allowed to pass through; transmissions beneath this threshold are filtered.

(human machine interface) An HMI is a device that displays process data to a human operator, who in turn uses the HMI to control the process.

An HMI is typically connected to a SCADA system to provide diagnostics and management data — such as scheduled maintenance procedures and detailed schematics for a particular machine or sensor.

Replacing a component with a like component while the system remains operational. When the replacement component is installed, it begins to function automatically.

(hypertext transfer protocol) A networking protocol for distributed and collaborative information systems. HTTP is the basis of data communication for the web.

In a programmable controller system, an I/O module interfaces directly to the sensors and actuators of the machine/process. This module provides electrical connections between the controller and the field devices.

International Electrotechnical Commission Carrier: Founded in 1884 to focus on advancing the theory and practice of electrical, electronics and computer engineering, and computer science. EN 61131-2 is the specification that deals with industrial automation equipment.

Institute of Electrical and Electronics Engineers, Inc.: The international standards and conformity assessment body for all fields of electrotechnology, including electricity and electronics.

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 — and a connection identifier.

Internet Protocol: That part of the TCP/IP protocol family that tracks the internet addresses of nodes, routes outgoing messages, and recognizes incoming messages.

ingress protection rating: A standardized approach to establishing the degree to which a device resists the ingress of particles and water, as defined by IEC 60529. For example:

A frequency-based filter that permits transmissions only below a pre-set frequency threshold to pass. In HART, the frequency threshold is typically set in range of 25 Hz: transmissions below this threshold—analog signals—are allowed to pass through; transmissions above this threshold—HART digital signals—are filtered.

Media Access Control address: A 48-bit number, unique on a network, that is programmed into each network card or device when it is manufactured.

An application layer messaging protocol. Modbus provides serial communications between master and slave devices connected on different types of buses or networks.

A multiplexer (MUX) is a device that selects one of several input signals and forwards the selected input into a single line.

Not a number: A numeric data type value representing an undefined or unrepresentable value.

National Electrical Manufacturers Association

protective ground: An equipment grounding conductor that keeps the exposed conductive surfaces of equipment at earth potential. A PE conductor does not enhance or facilitate the operation of the equipment. Its purpose is to guard the operator against potential electric shock. Contrast: functional ground (FE).

Programs to control machine operation are typically stored in non-volatile memory. A PLC is designed to provide highly deterministic performance, within predictable time boundaries.

In HART, when two master devices are connected to the HART communication network, the HART controller. The HART primary master is typically asset management software resident on a PC.

radio frequency interference: See EMI.

The originator of I/O connection requests for implicit messaging in EtherNet/IP, and message requests for Modbus TCP.

In HART, when two master devices are connected to the HART communication network, a hand-held master device temporarily connected to the network.

safety extra low voltage: A secondary circuit designed so that the voltage between any 2 accessible parts (or between 1 accessible part and the PE terminal for Class 1 equipment) does not exceed a specified value under normal conditions or under single point of failure conditions. Schneider Electric's Phaseo ABL8 range of power supplies has products that comply with the SELV standard in IEC/EN 60364-4-41.

An output that, when turned on, receives DC current from its load.

A load with a current directed into its input; it is driven by a current source.

transmission control protocol:. A connection-oriented transport layer protocol that provides full-duplex data transmission. TCP is part of the TCP/IP suite of protocols.