Table 923: Line data communication module
Characteristic Range or value
Type of LDCM Short range (SR) Medium range (MR) Long range (LR)
Type of fiber Graded-index
multimode
62.5/125 µm
Singlemode 9/125
µm
Singlemode 9/125 µm
Peak Emission
Wave length
Nominal
Maximum
Minimum
820 nm
865 nm
792 nm
1310 nm
1330 nm
1290 nm
1550 nm
1580 nm
1520 nm
Optical budget
Graded-index
multimode 62.5/125
mm,
Graded-index
multimode 50/125
mm
13 dB (typical
distance about 3
km/2 mile *)
9 dB (typical
distance about 2
km/1 mile *)
22 dB (typical
distance 80 km/50
mile *)
26 dB (typical distance 110 km/68
mile *)
Optical connector Type ST Type FC/PC Type FC/PC
Protocol C37.94 C37.94
implementation **)
C37.94 implementation **)
Data transmission Synchronous Synchronous Synchronous
Transmission rate /
Data rate
2 Mb/s / 64 kbit/s 2 Mb/s / 64 kbit/s 2 Mb/s / 64 kbit/s
Clock source Internal or derived
from received
signal
Internal or derived
from received signal
Internal or derived from received
signal
*) depending on optical budget calculation
**) C37.94 originally defined just for multimode; using same header, configuration and data format as
C37.94
21.2.16 Galvanic X.21 line data communication (X.21-LDCM)
21.2.16.1 Introduction
The galvanic X.21 line data communication module is used for connection to
telecommunication equipment, for example leased telephone lines. The module
supports 64 kbit/s data communication between IEDs.
Examples of applications:
• Line differential protection
• Binary signal transfer
Section 21 1MRK502052-UEN B
IED hardware
1192
Technical manual
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