The start and stop flags are composed of 0111 1110 sequence (7E hexadecimal) as
defined in the HDLC standard. CRC is designed according to the standard CRC16
definition. The optional address field in the HDLC frame is not used but, instead,
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 up
the messages. 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.
If communication is used for line differential purposes, 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.
If communication is used exclusively for binary signals, full data capacity of the
communication channel is used for the binary signal purpose which gives the
capacity of 192 signals.
In 2 Mbit mode, telegrams are still sent using C37.94 but the HDLC part is not
used. Instead, all 12 channels of the C37.94 frame are used, and a telegram is sent
whenever a sample is available. The address field is used in the same way as in 64
kbit mode but the CRC field is 32 bits. It carries 9 analog samples and 192 general
purpose binary signals.
GUID-E8E1B062-7E32-4850-A5D1-6EDBC82154D4 v1
IEC10000071 V1 EN-US
Figure 45: Setting example with one communication channel for binary
transfer
4.8.2 Configuration of binary inputs and outputs
GUID-89D944D1-DD6C-4666-8AA6-38FE5F366095 v1
GUID-0918C53D-F755-4FA1-BB3C-F672AFC6A7D2 v1
Signals are available in the Signal Matrix Tool (SMT) and as
hardware channels in the Application Configuration Tool (ACT).
Section 4 1MRK 505 382-UEN B
Analog and binary signal transfer for line differential protection
54 Communication set-up 670/650 series 2.2
Application Guide
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