Device Profile / IO-Link Version
Smart Sensor Profile is the standardized device profile for measuring sensors and includes the standard functions of IO-Link devices. This ensures a consistent appearance and functionality, regardless of the manufacturer of the connected device.
IO-Link specifications are constantly being improved. Version 1.1 was introduced as an improvement from the original version. This version provides data storage, mandatory data transmission rate, and transaction data transmission of up to 32 bytes per port.
Port Type / Power Consumption / Cable Length
Ports are IO-Link communication channels between the device and the master. In general, there are two types of ports in the specification for IO-Link masters: Port Class A (type A) and Port Class B (type B). IO-Link devices are connected to the master via standard unshielded 3-, 4- or 5-wire cables up to 20 m long. IO-Link requires only 3 wires each. The supply voltage is located on pins 1 and 3 (24 V, maximum 200 mA), while pin 4 is the communication output.
Transmission Speed / Conversion Time / Transaction Data Size
IO-Link devices support a data transmission rate specified in the IO-Link specification. The specified data transmission rates for IO-Link V1.1 are: COM1 = 4.8 kBaud, COM2 = 38.4 kBaud, COM3 = 230.4 kBaud.
The cycle time provides information about the time intervals during which the Master can access the device. Sensor technology (physical principle) has a large impact on cycle time. The minimum cycle time is stored in the IODD. Devices with different minimum cycle times can be configured on a single master.
Process data is transmitted cyclically in the form of a data telegram. Transaction data size is determined by the device.
SIO Mode / DI Mode
Each port of the IO-Link master can be operated in SIO mode (standard input-output mode: DI mode for sensors and DQ mode for actuators according to the latest specification) or in IO-Link mode and can thus process the information of all sensors. In SIO mode, the dual switching output (NPN, PNP or push-pull) of the sensor is used. In IO-Link mode, the sensor's output (pin 4) is used as a bi-directional, digital interface to exchange measurement and diagnostic information.
Dual Channel
Dual Channel transmits additional input and output signals in parallel with the IO-Link channel. Sensor operation provides maximum flexibility by using one channel or both simultaneously. This is also possible if the sensor has more than one dual channel.
Depending on the control concept, dual channels can serve different purposes. In applications with very high real-time requirements, it may be useful to connect the dual channel directly to an actuator to eliminate the delay caused by the controller's cycle time. This allows, for example, to trigger automatic format alignment or evaluate secondary data using IO-Link communication simultaneously.
If process control is primarily achieved via analog dual channel, the IO-Link interface can provide support for parameterization or downtime monitoring during installation. Plus, it can always be modified to work with digital controllers.
Transmission Quality / Security
The transmission and conversion of analog data is replaced by the transmission of digital data directly to the controller, which guarantees high and lossless data quality. IO-Link is a very robust communication system.
This communication system operates at 24 V level. If the transmission fails, the telegram is repeated two more times. Only after the second retry has also failed does the IO-Link Master detect that there has been a communication interruption and notify the higher-level controller.
IODD Identity Data
Every IO-Link device has a device description file, i.e. IODD (IO Device Description). This file contains data such as manufacturer information, article number, functionality, software version, etc., and this data can be easily read and processed by the automation system. Each device, i.e. each sensor, can be uniquely identified through both the IODD and the internal device ID. The sensor's identification data also includes device or application descriptions that the user can freely assign. The IODD consists of a main file and optionally external language files (both in XML format) and image files (in PNG format).
Adjustable Switching Sensor
Sensors compatible with IO-Link 1.1 can be operated as "Adjustable Switching Sensor (AdSS)" or "Digital Measurement Sensor (DMS)" according to the Smart Sensor Profile. When used as AdSS or DMS, Sensor-Master communication takes place via a completely standardized command set. Therefore, operation is also possible without the IODD file, which can significantly reduce integration costs. To find out whether a particular sensor has AdSS or DMS features, please refer to the datasheet.
Offline Parameterization
Offline parameter settings of the sensors can be made via convenient interfaces on the PC (via USB Master) or via the Wireless App (via Wireless Master). The sensors can be conveniently configured at the desk and installed without the need for additional teach-in.
Even if IO-Link is not implemented in machine control, sensors can be operated in SIO mode and benefit from this advantage.
Parameterization with Control Engineering Tool
Programmable logic controllers (PLC) are programmed using software called engineering tools (PC software). IO-Link sensors can be integrated directly into these engineering tools. Parameter settings of the integrated sensor can also be made via the engineering tool.
Parameter Memory During Sensor Replacement
When a sensor integrated in an automation system needs to be replaced (in case of failure), an unconfigured spare sensor can be easily integrated into the system and the parameter data of the faulty sensor is automatically assigned by the master (parameter server of the master). Parameter data is stored in both the sensor and the master (data storage).
Automatic Recipe / Format Change
Machines need to be reparameterized more frequently during operation to produce new recipes or formats. IO-Link sensors can automatically accept parameter sets stored in the control program. This ensures minimum setting change times.
find-me
Signaling to locate and physically identify a sensor in a machine or system, for example by flashing the LEDs on the sensor. This signal can be triggered, for example, from the controller's engineering tool.
Wide Setting Options
To solve applications reliably and efficiently, sensors can be teach-in according to the relevant process conditions. Teach options on the sensor may be limited, but IO-Link offers a wider range of settings. In addition to the classic teach options, advanced settings such as filter functions, switching hysteresis, switching window or temperature compensation are also available via IO-Link. User interfaces on PC or mobile devices make these settings user-friendly. Additionally, a programmable access lock (qTeach Lock) prevents direct manipulation of the sensor.
Transaction Data Transferred Cyclically
Unlike conventional sensors, multiple process data (e.g. switching signal + distance + frequency) can be output simultaneously via the same channel via IO-Link. Process data is cyclic data that is transmitted regularly and quickly (the maximum achievable speed corresponds to the cycle time of the automation system). This data is used for process control in the automation system. Via the IO-Link master and protocols such as OPC UA or JSON, this data can be transferred not only to the controller, but also to other IT systems (cloud).
Additional Data Available Out-of-Loop
With IO-Link, Baumer sensors can perform and output additional evaluations beyond standard operations. These analysis functions do not have to be programmed separately in the controller and can be used out-of-loop for evaluation when necessary. Examples: Number of switching cycles, operating time, power-on cycles, histograms of process data, operating voltage or device temperature. This additional data is also called "diagnostic data" and can be used, for example, in predictive maintenance applications.
