User's Manual
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7.1 Digital point-to-
point connection
Three-conductor
physics
Communications
mode
Interleave mode
IO-Link integrates conventional and intelligent actuators and sensors into automation systems.
Mixed use of traditional and intelligent devices is possible with no additional effort.
IO-Link is intended as a communications standard below the traditional fieldbus level. Fieldbus-
neutral IO-Link transmission uses existing communications systems (fieldbuses or Ethernet-
based systems).
The actuators and sensors are connected in point-to-point using conventional unshielded
cables.
IO-Link devices can send application-specific parameters and data (e.g. diagnostics data) using
a serial communications procedure. Flexible telegrams are possible for sending larger quantities
of data. Communication is based on a standard UART protocol with 24V pulse modulation. Only
one data line is used, which carries both the controller as well as the device telegram. This
means that conventional 3-conductor physics is possible.
IO-Link supports both communication mode as well as standard IO mode (SIO). Standard IO
provides a switching signal on the communication line such as used by normal binary switching
sensors. This mode is only possible with devices using 3-conductor connection technology.
Fig. 22: 3-conductor physics of IO-Link
The BIS L-409-... supports both modes. In SIO mode the signal “Data carrier in range” (24V) and
“No data carrier in range” (0 V) is made available to the host system as a switching signal.
If the BIS L-409… is not used with an IO-Link Master and without triggering IO-Link communica
-
tion, it works in SIO mode and can be operated on a digital input.
The BIS L-409-... works in communication mode with Frame Type 1. In this transmission type 2
bytes of process data or required data are sent per frame (data block). This can take place either
from IO-Link Master to device or vice-versa. Process data are the application-specific data, and
required data may contain parameters, service or diagnostic data.
So-called “Interleave Mode” makes it possible to send larger quantities of data. There multiple
Type 1 frames must be combined into a sequencer. One frame with process data and one with
required data are sent in alternation.
With the BIS L-409 a sequence consists of 32 individual frames. 8 bytes of process data are
sent in each direction per sequence. These process data are shown in greater detail in
Section
10.4 “Protocol sequence” on page 42
.
IO-Link Basics
7
BIS L-409 IO-Link Device
Processor