Balluff BVS ID-M1280 F1 Series, Configuration Manual

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BVS ID-M1280xF1-xx-xxx
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4.3 IO-Link / Fieldbus Process Data Protocol
4.3.1 Introduction
IO-Link integrates conventional and intelligent actuators and sensors in automation systems, whereby mixed
operation is possible without additional effort. IO-Link is intended as a communication standard below the
classic fieldbuses. As a fieldbus-independent transmission, IO-Link uses existing communication systems
(fieldbuses or Ethernet-based systems). IO-Link devices can transmit application-specific parameters and data
(e.g. diagnostic data) via a serial communication method. Flexible telegram lengths are possible in order to
transfer extensive amounts of data. Communication is based on a standard UART protocol with 24 V pulse
modulation. Only one data line is used for communication, over which both the controller and the device
telegram are transmitted. In this way, classic three-wire physics is possible.
4.3.1.1 Three-wire physics
IO-Link supports both communication mode and standard IO mode (SIO). Standard IO provides a switching
signal on the communication line, as used by simple switching sensors. This mode is only available on devices
that use three-wire connection technology.
4.3.1.2 Communication mode
The BVS ID - IO-Link device operates in communication mode with 32 bytes (or 31 bytes of input buffer for
CCM variant) of process data transferred in both directions, 2 bytes of which are synchronization data (1st and
2nd bit string).
For the exchange of data and commands between BVS ID and the controlling fieldbus system, two buffers are
required. The input buffer is provided by the BVS ID and read by the PLC. The output buffer is written by the
PLC and then read by the BVS ID read. The exchange of the buffer contents is performed by means of cyclic
polling. When writing the buffer, the transferred data of the previous cycle is overwritten. The contents of the
input and output buffers are not deleted after reading.
32 bytes can be transferred in one processing cycle. If now larger amounts of data are to be transferred, these
are transferred sequentially with the so-called
toggle mechanism are transferred. A complete transfer cycle is
executed with the double bit string secured. If the first byte (1st bit string) matches the last byte (2nd bit
string), valid information is present in the intermediate bytes.
Based on the connected communication system (PLC or PC) the byte orientation of 32 bit data must be
adapted.
The
Endianness describes the memory organization for simple numerical values, primarily the storage of
integer values (integers) in the working memory. Here the BVS ID can be adapted to the connected control
system. The Endianness can be defined in the BVS ID can be set:
Big Endian:
The most significant byte is stored first, i.e. at the smallest memory address.
Little Endian:
The least significant byte is stored at the starting address.