Beckhoff EPI4 Series, Documentation

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IO-Link basics
EPI4xxx, ERI4xxx 16 Version: 1.6
3.2 Establishment of IO Link communication
The establishment of the IO-Link communication is illustrated in Fig. Establishment of IO-Link
communication. This illustrates in particular the sequence when automatically scanning [ } 34] the IO-Link
port.
Fig. 2: Establishment of IO Link communication
• If an IO-Link device is connected to a master port, the master attempts to establish communication. A
defined signal level, the wake-up pulse , signals to the device that UART bytes are to be sent from now
on.
From this point on, all data will be interpreted by the IO-Link device as UART bytes.
• The master runs through all baud rates [
}
17] , starting with the fastest baud rate
(COM3 = 230 kbaud). A successful connection has been established when the slave responds to the
wake-up pulse.
• First of all the master reads the basic parameters (Vendor ID, Device ID, process data length,
telegram type and cycle time) and compares them with the existing configuration.
• If no connection could be established to the device, or if the saved parameters differ from those read,
the corresponding error is output.
• If the saved parameters differ from those read, the IO-Link device changes to the PREOP state.
If the IO-Link device specification is V1.1, the parameter server [
}
17] is now executed. If the IO-Link
device specification is V1.0, this step is omitted and the device changes directly to OP.
• Finally the cycle time is written and the device changes to OP. After that the master cyclically
exchanges data with the device.