IO-Link Glossary

COM
Describes an operation mode, in which messages are transfered via a IO-Link communication between a device and a master and represents one of the three possible SDCI communication modes "COM1", "COM2" or "COM3".

SDCI communication mode
Fundamental IO-Link technology. A digital interface that enables communication from point to point.

Device type manager
Device driver component for a device in an FDT environment. A DTM can represent the functionality of a device via a graphical user interface. A DTM runs in an FDT frame application (e.g., PACTware) or in control systems with FDT interfaces.

Digital input
Interface of a device that digitally evaluates a signal via its level and generates binary information from it.

Digital output
Interface of a device that generates a signal with 2 levels from binary information in order to control other devices with it. Example: Typical actuator like a solenoid valve.

Event
An "event" is to be regarded independently of interfaces used for communication.
IO-Link context: An IO-Link device can indicate a diagnostic status to an IO-Link master by means of an event. An event code is transmitted providing the master with detailed information on the cause of the event. The master processes the event accordingly.

FDT
Concept for using device type managers manufacturer-independently in different applications. FDT can be used to integrate field devices from different manufacturers into automation systems. FDT works on Microsoft COM/DCOM technology and provides a manufacturer-independent basis to access all communication and application features of a device for system-wide configuration and diagnostics. Example of an FDT: PACTware™.

IO Device Description
XML-based, static functional description file of an IO-Link device. The IODD contains the data model of a device, supported variants, the description of a user interface, as well as a textual description of parameters and data. The IODD can consist of multiple files that describe the sensors and actuators of IO-Link configurations. 

IO-Link
Input/output connection line for data transfer over a standard M8 or M12 plug to enable the intelligent communication of sensors and actuators on the field level.

IO-Link device
Reacting participant in an IO-Link communication with an IO-Link master. An IO-Link device can alternatively be operated in the standard IO mode and is then compatible for use with digital inputs (DI) according to IEC 61131-2. Component of an IO-Link communication that fully supports the IO-Link standard IEC 61131-2. An IODD is available for the device. In technical and normative terms, an IO-Link device is a SDCI device.

IO-Link master
Component of an IO-Link communication that fully supports the IO-Link standard and contains one or more IO-link ports. As an acting participant, the IO-Link master initiates the IO-Link communication with a connected IO-Link device and regularly carries out requests. The IO-Link master usually makes the data available to a higher-level communication system via a gateway or converts requests from the gateway to IO-Link.

IO-Link port
Designates the physical terminal / connector or logical channel for connection of an IO-Link device.

Parameter server
Central entity that contains parameter sets (parameter and configuration data) from different devices and distributes or loads them on command. A parameter server contains a mirror image of the necessary settings of the various devices of an automation application.

Parameter server function
Functions and methods used by a parameter server. The prerequisite for using this function is the implementation of the IO-Link specification V1.1 in the IO-Link master and in the IO-Link devices. 

Process data
Data from or to a device that is required for the automation of a process. Process data is transferred cyclically between the device and the control unit. In general, the behavior of the automation application is to be made predeterminable. Examples of process data are: Measured values, switching signals, control signals, output values.

Point-to-point connection
A data link established between only two data stations.

Service data
A cyclic data transmitted from a device upon request of the master application. Examples are parameter data, event data or diagnostic data.

Standard input and output 
IO-Link port operation mode in accordance with digital inputs and outputs defined in IEC 61131-2. This operation mode is established after power-up, fallback, or unsuccessful communication attempts.

Device
Device that receives a signal output from a master signal and reacts accordingly. In bus technologies: A passive bus device.

Programmable logic controller
System used to control and regulate processes in machines and plants. Measured values or status information are processed via an application-specific program and the machine is controlled via set values or control signals. This way the PLC can be applied in various environments. The PLC can be used as part of a DCS.

Cycle time
Regarding PLCs, the cycle time denotes the time it takes between reading in the inputs and outputting the outputs. In communication systems, the cycle time denotes the duration until all data is exchanged with all participants and the communication process starts again.