Interfaces; Io-Link Interface - Balluff BML Información Básica

Interfaces for BML Magnetic Encoder System
2

Interfaces

2.1

IO-Link interface

IODD and XML file via download on the Internet
at www.balluff.com or email to
[email protected].
Additional information and descriptions of the
protocol and profiles can be found at
https://www.io-link.com.
General
IO-Link integrates conventional and intelligent sensors and
actuators in automation systems and is intended as a
communication standard below classic field buses. Field-
bus-independent transfer uses communication systems
that are already available (field buses or Ethernet-based
systems).
IO-Link devices, such as sensors and actuators, are
connected to the controlling system using a point-to-point
connection via a gateway, the IO-Link master. The IO-Link
devices are connected using commercially available
unshielded standard sensor cables.
Communication is based on a standard UART protocol
with a 24-V pulse modulation in half-duplex operation. This
allows classic two- or three-conductor physics.
Protocol
With IO-Link communication, data are cyclically exchanged
between the IO-Link master and the IO-Link device.
In this protocol, both process and required data, such as
parameters or diagnostic data, is transferred. Process data
are cyclically sent at the set cycle time. Transmission of
required data may take several cycles.
IO-Link communication is initialized essentially by the
master and the device responds to the master inquiries.
Cycle time
The cycle time (Master Cycle Time) is determined by the
following two parameters: the minimum possible cycle time
prescribed by the IO-Link device (Min Cycle Time) and the
minimum cycle time of the master. The cycle time is
automatically set by the master such that it corresponds to
the capabilities of both components.
www.balluff.com
Protocol version 1.0 / 1.1
In protocol version 1.0, process data larger than 2 bytes
was transferred spread over multiple cycles.
From protocol version 1.1, all available process data is
transferred in one frame. Thus, the cycle time (master cycle
time) is identical to the process data cycle.
The Balluff BML sensors correspond to protocol
version 1.1. Operating the IO-Link device on an
IO-Link master with protocol version 1.0 results
in longer transfer times (process data cycle ~
amount of process data × master cycle time).
Index/Subindex
Parameter access is basically via the Index/Subindex.
Various indices are defined by the IO-Link standard. For
example indices for system commands, identification and
parameter management are prescribed. In addition Balluff
defines its own indices. These can be found in the user's
guide for the respective sensor or in the IODD.
Parameter management
A parameter manager that enables device parameters to
be saved on the IO-Link master is defined in protocol
version 1.1. When exchanging an IO-Link device, the
parameter data of the previous IO-Link device can be
taken over. The operation of this parameter manager is
dependent on the IO-Link master and is explained in the
corresponding description.
Error messages
The following error messages are stored for failed
parameterization:
Error code Error message
0×8011 Index not available
0×8012 Subindex not available
0x8020 Service temporarily not available
0×8030 Value out of range
0×8033 Parameter length overrun
0×8034 Parameter length underrun
0×8036 Function temporarily unavailable
0×8040 Invalid parameter set
0×8082 Application not ready
Tab. 2-1: IO-Link specification error messages
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