Protocol Sequence - Balluff BIS U-4A7-082-01C-07-S4 Betriebsanleitung

BIS U-4A7-082- _1C-07-S4
Industrial RFID system - Read/write head
8
System integration (continued)
8.6

Protocol sequence

If communication is triggered by the IO-Link master, then
transmission of the respective current process data begins.
The bit strings of the output buffer can be used to control
the device. For example, the device can be restarted by
setting the GR bit or a new assignment can be transferred
by setting the AV bit. In addition, this controls the data
flow. By inverting the TI bit, the controller can indicate that
the data of the input buffer has been read or that new data
has been provided in the output buffer. The meaning
depends on the current command.
Each bit must be set or cleared in the first as well as in the
second bit string, so that the change is accepted by the
device. All further necessary command or data contents
must be valid beforehand. As long as the bit strings are not
identical, no data is accepted. This ensures that only
completely transmitted data is accepted.
The status of the device is displayed in the input buffer.
Here, for example, the AF bit indicates an error in the
current assignment or the HF bit indicates that the head is
currently switched off. In addition, read data and status
codes are transmitted via the input buffer. If no data carrier
is present, the last current data is displayed in the input
buffer. The deleted CP bit indicates that there is no data
carrier in the field. If the MT bit is set, there is more than
one data carrier in the field.
The status of the bit is only valid if the two bit strings show
an identical value. Then it is guaranteed that the remaining
data contents are also current.
All of the functions of the read/write head can be used in
this way (see chapter 8.7 on page 44).
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