Interface Configuration Guide 7705 SAR Interfaces
Edition: 01 3HE 11011 AAAC TQZZA 173
For both master and slave applications, the 7705 SAR must be physically connected
to the SCADA device by one of the following:
• a 7705 SAR-8 or 7705 SAR-18 using the 12-port Serial Data Interface card
(supports both RS-232 and X.21 links)
• a 7705 SAR-H using the 4-port T1/E1 and RS-232 Combination module
(supports RS-232 links only)
• a 7705 SAR-Hc using an on-board RS-232 serial port (supports RS-232 links
only)
The 12-port Serial Data Interface card also supports an RS-530/RS-422 interface
with the use of an adapter cable that connects to a DB15 connector on the front of
the X.21 distribution panel. There is no configuration specifically for the
RS-530/RS-422 interface; configuration is done in X.21 mode and applies to the
RS-530/RS-422 interface when it is physically enabled through hardware. For
information about 12-port Serial Data Interface card adapter cables, see the
7705 SAR Serial Data Interface Card Installation Guide.
The remote nodes are connected to the SCADA bridge over an IP/MPLS network.
An Integrated Services card supports up to 16 SCADA bridges. Each bridge supports
32 branches. Two branches (branch 1 and branch 2) are dedicated connections to
the SCADA masters; the other 30 branches connect to the slaves. An MDDB SCADA
bridge is created using the config>scada bridge-id command and a branch is
created using the config>scada>branch branch-id command.
Figure 24 shows a typical SCADA MDDB network. A Cpipe SAP is configured for
each master and slave branch in order to transmit data to the bridge.
The RS-232/X.21 traffic is converted to a 64 kb/s Cpipe using high capacity
multiplexing (HCM). The Integrated Services card terminates the Cpipe (the slaves
send data back over the IP/MPLS network), recovers the data directly from the Cpipe
as an HCM frame, and sends the data to the bridge.
Note: Larger bridges can be built by cascading individual bridges internally within a single
Integrated Services card and using the master output from one bridge as the slave input to
another bridge. Larger bridges can be cascaded across multiple Integrated Services cards
by using an RS-232 link or an X.21 link.
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