ABB REB670 Applications Manual page 462

Section 17
Remote communication
456
IEC06000519 V2 EN
Figure 191: Direct fibre optical connection between two IEDs with LDCM
The LDCM can also be used together with an external optical to galvanic G.703 converter
or with an alternative external optical to galvanic X.21 converter as shown in figure 192.
These solutions are aimed for connections to a multiplexer, which in turn is connected to
a telecommunications transmission network (for example, SDH or PDH).
Multiplexer
*) Converting optical to galvanic G.703
IEC05000527 V2 EN
Figure 192: LDCM with an external optical to galvanic converter and a multiplexer
When an external modem G.703 or X21 is used, the connection between LDCM and the
modem is made with a multimode fibre of max. 3 km/2 mile length. The IEEE/ANSI
C37.94 protocol is always used between LDCM and the modem.
Alternatively, a LDCM with X.21 built-in converter and micro D-sub 15-pole connector
output can be used.
Telecom. Network
*)
1MRK 505 337-UUS -
en06000519-2.vsd
Multiplexer
*)
en05000527-2.vsd
Application manual