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User Manual
E727T0005, valid for E-727
BRO, 2019-06-28
Physik Instrumente (PI) GmbH & Co. KG, Auf der Roemerstrasse 1, 76228 Karlsruhe, Germany
Page 150 / 240
Phone +49 721 4846-0, Fax +49 721 4846-1019, Email
Connection Lost
When the connection is lost during the transfer of a data stream then the transmission must be
aborted. For this purpose the number of CRC-errors should be counted which occur during the
transmission of a data stream. When the CRC-error counter reaches a threshold then the
transmission will be aborted.
It is up to the sender to set the threshold value where it aborts the transmission.
Because the sender tells the start of the transmission of a data stream the receiver will always be
synchronized with the sender. So it is not necessary for the receiver to check the connection.
Transport Layer Flow Charts
The following flow charts show the transfer of data streams via data segment 2. It is shown for
sender and receiver side separately.
The flow charts do not show the transfer of the flag bits. Note that these bits are always
transferred when data segment 2 is not used for data stream transfer.
Nomenclature
The following names are used in the flow charts:
CTR2.SToggle, CTR2.TwoBytes, CTR2.DataCtrl: Control bits for data segment 2 as
they are sent with the data packet
DataCtrlReg: Buffer of DataCtrl bits which are set for data transfer. When data is
sent then these bits are copied to CTR2.DataCtrl.
ST.CRCError, ST.RToggle, ST.ACK: Status bits which are set and sent by the receiver.
SToggleRegister: Toggle register implementation on sender side
RToggleRegister: Local copy of toggle register on sender side.
DataSegment2.Byte1, DataSegment2.Byte2: Data bytes transferred by data segment
2. Loading data segment 2 bytes with current flag bits while dummy packets are sent
is not shown by the flow charts.