Traditionally, the control world could only accept binary or analog signals and, therefore, only had limited information. More data required more inputs or analog cards, which are expensive and require more labor for wiring.
Today’s sensors process a lot of data, but without a pathway to the controller, it is trapped inside the sensor.
In general, IO-Link offers three types of data that vary from sensor to sensor. They are cyclic, acyclic and events data.
|Digital measurements values (Cyclic data)
This type of information is requested continuously from the controller and is needed to control machines or processes.
|Internal data memory (Acyclic data)
This type of information is requested (on demand) only when you need it.
Additional specific diagnostic data from the sensor.
The example below shows the difference between traditional outputs available for a flow meter vs. the data available via IO-Link.
Only 2 wires available - user must choose
|Available process data via IO-Link
All data available over 1 wire
|• Switching output for flow||Cyclic data (continuously transmitted)|
|• Switching output for temperature||• Flow rate|
|• Pulse output for totalization||• Temperature|
|• Frequency output for flow||• Totalized volume|
|• Frequency output for temperature||• Device status|
|• Input counter reset||Acyclic data (available when called on demand)|
|• Max and min flow rate|
|• Max and min temperature|
|• Totalizer memory|
|• Serial number and revision verfication|
|• Simulation mode|
|• Configuration parameters|
|Events data (diagnostic and other sensor specific information)|
|• Incorrect parameters|
|• Sensor out of range|
With IO-Link, all data is available via industry standard 3-wire cordset. No additional PLC inputs required.
ifm provides startup packages that aids in integration of our IO-Link products with a short learning curve. Whether you are a PLC expert or a novice, our guides lead you through the setup process. IO-Link can be integrated into many of today’s PLC platforms.
Startup packages: https://www.ifm.com/us/en/downloadarea/IOMasterContent
The video below illustrates our user-friendly Add-on Instructions (AOI) for integration with Rockwell/Allen Bradley PLCs. Other integration support videos can be found on our System integration site.
The I/O Device Description (IODD) contains details of the information available from the device such as identity, parameters, process data, diagnostic data and communication properties.
The IODD is downloaded typically as a .zip file and it contains a .xml file and product photos.
Typically, an engineering software like ifm’s LR Device configuration software and some PLCs can directly use an IODD file. In most cases, however, it is not needed to work with an IO-Link device. You simply need to understand what data is possible via the IODD .pdf description file.
ifm publishes the PDF file in a readable format to help you understand the information you can access via the PLC / controller.
The document contains details on three types of data – cyclic, on demand, and diagnostic.
Most IO-Link masters use A ports as defined by the IO-Link consortium. Some output devices like valve manifolds and smart LED lights typically require B ports because of the extra power requirements of the devices.
On A ports, pin 2 is always used as a digital input and pin 5 is not connected. ifm's DataLine (AL13xx) and CabinetLine (AL19xx) masters are offered with only A ports. These devices are limited to 300 mA load current per port.
On B ports, pins 2 and 5 provide an additional isolated supply voltage to connect IO-Link output devices that require increased power. With the introduction of the PerformanceLine masters (AL14xx), we can now switch loads up to 2A.