Technical Data; Communication Via Built-In X.21 Galvanic Interface - ABB Relion 670 Series Application Manual

1MRK 505 382-UEN E
A maximum of 10 meter of cable is allowed to ensure the quality of the data (deviation from
X.21 standard cable length).
Synchronization
The X.21 LDCM works like a DTE (Data Terminal Equipment) and is normally expecting
synchronization from the DCE (Data Circuit Equipment). The transmission is normally
synchronized to the Signal Element Timing signal when a device is a DTE. When the signal is
high it will read the data at the receiver and when the signal is low it will write data to the
transmitter. This behaviour can be inverted in the control register.
Normally an external multiplexer is used and it should act like the master.
When two X.21 LDCM is directly communicating with each other one must be set as a master
generating the synchronization for the other (the slave). The DTE Signal Element Timing is
created from the internal 64 kHz clock.
The Byte Timing signal is not used in ABB devices.
5.4.4

Technical data

Table 25:
Quantity
Connector, X.21
Connector, ground selection
Standard
Communication speed
Insulation
Maximum cable length
5.4.5

Communication via built-in X.21 galvanic interface

LOCAL
IEC07000259 V2 EN-US
Figure 67: Communication structure via built-in X.21 galvanic interface
IED
X.21
Communication set-up, 670/650 series
Application Guide
Galvanic X.21 line data communication module (X.21-LDCM)
< 10 m
IED PCM
Built-in X.21
galvanic
interface
Terminal used for binary signal transfer
Built-in galvanic iterface
© Copyright 2017 ABB. All rights reserved
Range or value
Micro D-sub, 15-pole male, 1.27 mm (0.050") pitch
2 pole screw terminal
CCITT X21
64 kbit/s
1 kV
10 m
< 10 m
PCM
Built-in X.21
galvanic
interface
Section 5
Communication set-up
GUID-83EC40D0-ABCF-4292-B3DF-155C3A556B76 v4
GUID-C0B90D43-0B15-4B17-835D-64114CF968E9 v1
REMOTE
IED
IEC07000259-2-en.vsdx
69