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Remote end data communication
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The start and stop flags are the 0111 1110 sequence (7E hexadecimal) defined in HDLC
standard. The CRC is designed according to standard CRC16 definition.
The optional address field in the HDLC frame is not used, instead a separate addressing
is included in the data field.
The address field is used for checking that the received message originates from the cor-
rect equipment. There is always a risk of multiplexers occasionally mixing up the mes-
sages. Each terminal is given different terminal numbers. The terminal is then
programmed to accept messages only from a specific terminal number.
If the CRC function detects a faulty message, the message is thrown away and not used
in the evaluation. No data restoration or retransmission are implemented.
The hardware, consisting of a Data communication module, is placed in an applicable
slot in the terminal. To add or remove the module, a reconfiguration of the terminal is
done from the graphical configuration tool, CAP.
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