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Rockwell Automation Publication IOLINK-UM001A-EN-P - August 2017
Chapter 1
836P Pressure Sensor with IO-Link Overview
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 allows for
selection of 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.
Accessing IO-Link Data
Cyclic Data
To exchange the cyclic process data between an IO-Link device and a
controller, the IO-Link data from the IO-Link master is placed on the address
ranges assigned beforehand. The user program on the controller accesses the
process values using these addresses and processes them. The cyclic data
exchange from the controller to the IO-Link device (for example, IO-Link
sensor) is performed in reverse.
Acyclic Data
Acyclic data, such as device parameters or events, are exchanged using a
specified index and subindex range. The controller accesses these using Explicit
Messaging. The use of the index and subindex ranges allows targeted access to
the device data (for example, for reassigning the device or master parameters
during operation).
Summary of Contents for Allen-Bradley 836P Series
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