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CRS-311 1:1 Redundancy Switch
Introduction
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The TMI can be completely removed from the CRS‐311, with cables still attached, and
traffic is not interrupted or affected.
Ease of Connection: Connection to the Traffic and Redundant Modems is simple. One cable
connected to the HD‐15 port on the TMI or RMI carries the Switch‐to‐Modem communications,
fault indications, and remote control.
•
For the CDM‐Qx/QxL: These modems require an additional EIA‐485 multi‐drop cable
from the Switch to all modems to provide remote control interface capability.
•
For EIA‐232/485 M&C User connections: A direct user‐to‐modem serial EIA‐232/485
communication connection is not permissible when connected to the CRS‐311. You
must instead connect to the DB‐9 "Remote" connector on the CRS‐230 System
Controller (installed on the CRS‐311). For detailed information on remote addressing
schemes, see Appendix C. ADDRESSING SCHEME INFORMATION.
TMI Monitoring: Terrestrial user clock and data signals to and from a Traffic Modem are routed
through the TMI via a set of relays. This is arranged so that the de‐energized (unpowered) state
connects the data signals directly through to the Traffic Modem. If the power supplies to the
system are lost or if the TMI carrying traffic is removed, no interruption of the traffic occurs.
Note also that, in normal circumstances where the Redundant Modem is not in service, no data
is carried through the CRS‐311 backplane – all data is routed via the TMI.
Data Interfaces: The CRS‐311 supports all of the standard and optional data interface types
available on the CDM‐Qx/QxL or the SLM‐5650/5650A modems, via the following TMIs:
•
CRS‐316 – EIA‐530 or Ethernet (via Ethernet Bridge Mode)
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CRS‐325 – G.703 (Balanced or Unbalanced)
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CRS‐336 – HSSI or Ethernet (via Ethernet Bridge Mode)
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CRS‐365 – Quad E1
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CRS‐515 – 4‐Port Ethernet (via Ethernet Bridge Mode, Ethernet Router Mode, or
Ethernet BPM (Bridge Point‐to‐Multipoint) Mode)
See Sect. 1.3.4.2 TMI Modules and Sect. 1.4.1 CRS‐311 Specifications for more information on
these interface modules and their specifications.
CRS‐281x Selection: The CRS‐281x switch module connects the online modulator's Tx IF signal to
the RF Up Converter. It also passively splits the Rx IF signal to provide both demodulators with
the same IF signal coming from the LNB, thus reducing switching time.
Three CRS‐281x switch modules are compatible for use with the CDM‐Qx/QxL modem:
•
CRS‐281 (70/140 MHz IF) with Type 'BNC' (50Ω) connectors
1–3
Revision 7
MN/CRS311.IOM
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