Siemens 7SG11 Technical Manual page 48

PSTN : Public Switched Telephone Network
Modem
Personal Computer
Modem
Personal Computer
- A more sophisticated version of the former configuration of
Figure 2. Several relays within the substation can be
accessed via one modem but only one can be communicated
with at a time.
PSTN : Public Switched Telephone Network
Modem
Personal Computer
Modem
Personal Computer
- Both Dialogue type and Automatic comms :
- Automatic type : continuous interrogation of all relays by
cyclical polling.
- Dialogue type comms. can be initialised from MMI also
©2011 Siemens Protection Devices Limited
Fibre-Optic Hub
Multiplexer
P
S
T
Modem
N
SIGMA-1
Figure 3 - Star Type Configuration (Multiplexer)
EMS Remote
Control Points
Data Concentrator /
Control system
P
S
T
Modem
N
Man-Machine
Interface
Figure 4 - Data Concentrator Configuration
7SG11 Argus 8 Communication Interface
Parallel hardwired connections
(clean contacts, binary inputs)
Classical
Serial optical
SCADA
links
Tx
Serial optical links
Rx
Tx
Rx
Tx
Rx
Cyclical
polling
Chapter 4 Page 7 of 8
EMS Remote
Control Points