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08.89
9 Appendix
9.2 LSV2 procedure
Text transfer phase
The transfer is executed in the transparent mode. In this mode, all text characters can be
coded as desired within a fixed character frame.
The DLE STX character sequence specifies the switchover to the transparent mode.
Switchback to the standard mode is by means of the DLE ETX character sequence. After an
error-free reception the receiving station acknowledges with DLE 1.
When the transmitting station receives this acknowledgement, it moves into the completion
phase and ends the transmission with EOT. On reception of EOT, the receiving station also
moves into the completion phase.
If the text is mutilated during transmission, the receiving station acknowledges with NAK and
waits for a new text transfer.
If the transmitting station receives a mutilated acknowledgement, this character is ignored and
the transmitting station sends a further acknowledgement request after the T1 monitoring time
has elapsed.
If on the other hand, the receiving station receives a mutilated control character, it does not
respond, and this error is only noticed after the monitoring time in the transmitting station has
expired.
Completion phase
In the completion phase, the transmitting station sends EOT thus moving into the initial state
(neutral state). If the receiving station receives the EOT undistorted, it also returns into the
initial state. If EOT is received by the receiving station with an error, either the T4 monitoring
time responds at the receiving station and the receiving station moves into the initial phase, or
the transmitting station moves again into an enquiry phase with ENQ and the receiving station
responds with DLE 1.
9–9
© Siemens AG 1989 All Rights Reserved
6FC5 197-0AB20-0BP0
SINUMERIK 840/880 (PJ)
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