XPS-E
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1. The data_exchange.req telegram is sent to XPS-E. XPS-E has already
received the first characters at the interface. It returns them in the
response telegram data_exchange.res to the Master. The confirmation
is incremented by 1 and the length of the reception data is entered.
Moreover, the status (S) of XPS-E is returned.
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2. New data_exchange.req telegram.XPS-E returns the new data by
incrementing the confirmation number by 1.
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3. As response telegram to the data_exchange.req telegram, XPS/XPS-E
enters the old confirmation number as no new data has been received
at the serial interface. The receive data length is set to 0.
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4. XPS-E has again received new data. The confirmation number is
incremented by one and the data returned correspondingly by the
data_exchange.res telegram to the Master.
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If no time guarantee can be given and if data loss has to be excluded
under all circumstances, XPS-E must be run in the request mode.
Serial triggered Mode
In serial triggered mode XPS/XPS-E waits for the termination of the
receive data by the trigger character defined within the external user
parameters of XPS-E (usually LF in ASCII-strings). The receive
confirmation number is not increased as long as no trigger character
is received. After the trigger character is received the Data Exchange
Resp.-buffer is updated with the received data inclusive the trigger
character. The data Exchange Resp.-buffer does not change as long
as the next trigger character is received.
Illustration 4:
Empfang im Seriell getriggerten–Modus(Endezeichen:0x0A)
x= Receive request number
S= Status
Data exchange