The start and stop flags are the 0111 1110 sequence (7E hexadecimal), defined in the HDLC
standard. The CRC is designed according to the 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 correct
equipment. There is always a risk that multiplexers occasionally mix the messages up. Each
terminal in the system is given a number. The terminal is then programmed to accept messages
from a specific terminal number. If the CRC function detects a faulty message, the message is
thrown away and not used in the evaluation.
When the communication is used for line differential purpose, the transmitted data consists of
three currents, clock information, trip-, block- and alarm-signals and eight binary signals which can
be used for any purpose. The three currents are represented as sampled values.
When the communication is used exclusively for binary signals, the full data capacity of the
communication channel is used for the binary signal purpose which gives the capacity of 192
signals.
19.2 Transmission of local analog data via LDCM to remote
end, function block LDCMTRN called LDCMTransmit
GUID-B057C0DD-4EA8-4F6A-B57C-3395DFB38463 v2
19.2.1 Function block
SEMOD171559-1 v1
GUID-05808CF6-34D6-4C76-A7A2-A26E5A96EC44 v2
LDCMTRN
^CT1L1
^CT1L2
^CT1L3
^CT1N
^CT2L1
^CT2L2
^CT2L3
^CT2N
IEC10000017-1-en.vsd
IEC10000017 V1 EN-US
Figure 619: LDCMTRN function block
19.2.2 Signals
PID-3823-INPUTSIGNALS v5
Table 940: LDCMTRN Input signals
Name Type Default Description
CT1L1 STRING 0 Input to be used for transmit CT-group1 line L1 to remote end
CT1L2 STRING 0 Input to be used for transmit CT-group1 line L2 to remote end
CT1L3 STRING 0 Input to be used for transmit CT-group1 line L3 to remote end
CT1N STRING 0 Input to be used for transmit CT-group1 neutral N to remote end
CT2L1 STRING 0 Input to be used for transmit CT-group2 line L1 to remote end
CT2L2 STRING 0 Input to be used for transmit CT-group2 line L2 to remote end
CT2L3 STRING 0 Input to be used for transmit CT-group2 line L3 to remote end
CT2N STRING 0 Input to be used for transmit CT-group2 neutral N to remote end
Section 19 1MRK 502 066-UUS B
Remote communication
1218
Technical manual
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