MSCDN – MP2A Communication Interface
©2010 Siemens Protection Devices Limited
Chapter 4 – Page 7 of 11
APPENDIX A - COMMUNICATION CONNECTIONS
Figures 1 to 6 illustrate a number of methods of connecting relays in communications networks.
Note that in the case of the optical ring configurations (Figure 4, Figure 6 and Figure 7), the Data Echo feature
must be switched ON in the communications settings menu of the relay. In all other cases this setting should
be set to OFF. In the data echo mode, everything that is received on the fibre optic receiver port is
automatically (in hardware) re-transmitted from the transmitter port. This is made possible because of the
communications standard IEC 60870-5-103 which operates half-duplex.
Personal Computer
Classical SCADA
EMS Remote
Control Points
Optical link
Parallel hardwired connections
(clean contacts, binary inputs)
1. Dialogue type comms (connection oriented)
2. Dialogue for purpose of analogue and digital fault
waveform extraction and display, setting display and change,
event display, instruments etc.
3. Manufacturer specific
Figure 1 - Basic Communications Configuration
