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Rockwell Automation Publication 871TM-UM002C-EN-P - October 2017
Chapter 3
871TM Long-range Sensor with IO-Link Overview
IO-Link Data Types
There are four data types available through IO-Link:
Process Data
The process data of the devices are transmitted cyclically in a data frame in
which the device specifies the size of the process data. Depending on the
device, 0…32 bytes of process data are possible (for each input and output).
The consistency width of the transmission is not fixed and is thus dependent
on the master.
Some devices can support multiple process data modes, which allow you to
select different cyclic process data themes.
Value Status
The value status indicates whether the process data is valid or invalid. The
value status can be transmitted cyclically with the process data.
Device Data
Device data supports device-specific configurable parameters, identification
data, and diagnostic information. They are exchanged acyclically and at the
request of the IO-Link master. Device data can be written to the device (Write)
and also read from the device (Read).
Events
When an event occurs, the device signals the presence of the event to the
master. The master then reads out the event. Events can be error messages and
warnings/maintenance data. Error messages are transmitted from the device to
the controller via the IO-Link master. The transmission of device parameters
or events occurs independently from the cyclic transmission of process data
(see
for device-specific events and associated codes).
Process data
→
Cyclic data
Value status
→
Cyclic data
Device data
→
Acyclic data
Events
→
Acyclic data