Nokia 7705 SAR - 3.6.2 PCM Multidrop Bridge

7705 SAR Interfaces
174
Interface Configuration Guide
3HE 11011 AAAC TQZZA Edition: 01
Figure 24 SCADA MDDB Network
3.6.2 PCM Multidrop Bridge
The pulse code modulation (PCM) multidrop bridge application provides multidrop
bridging for SCADA systems that use 4-wire analog modems to connect remote
slaves to a master. Incoming analog signals from the master are converted to PCM
(Mu-Law or A-Law) for transport between a remote slave and the master. The
Integrated Services card broadcasts the master stream to all remote slaves. Only the
addressed remote unit will respond to the broadcast and the response must be
transported through the bridge back to the master via an E&M interface. If the
network RTUs support two SCADA systems over the same interface by separating
them into high-frequency and low-frequency bands, the PCM multidrop bridge
always selects the two loudest branches to be passed through the bridge for
communication with the master.
23918
Master “A”
Master “B”
SAP
SAP
SAP
SAP
SAP
SAP
ISC
Cpipe
Cpipe
Cpipe
Cpipe
7705 SAR
(SAR-8 or SAR-18)
SAP
Cpipe
7705 SAR
(SAR-8, SAR-18,
SAR-H, or SAR-Hc)
Remote site
SDP
SDP
RS-232/
X.21
RS-232/
X.21
RS-232/
X.21
SDP
SAP
Cpipe
7705 SAR
(SAR-8, SAR-18,
SAR-H, or SAR-Hc)
Remote site
RS-232/
X.21
SDP
IP/MPLS
network
SCADA bridge configured on
the Integrated Services card
Note: E&M signaling transport through the bridge is not supported.