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Line Interface Modules
Subrate LIM
The Subrate LIM is only available for the OCM-1000 system. The Subrate LIM is an ITU-T V.28/
EIA/TIA-232-E interface that works at various aggregate rates up to 64 kbps. Typically, it
interfaces with the GDC SpectraComm V.F 28.8 modem (G- or higher) and is used over analog
lines. The Subrate LIM requires OCM-1000 software V1.3 or higher and E- CCM firmware or
higher. The Subrate LIM also provides the following features:
•
Provides N times 2400 rates from 9600 to 45,600 bits per second
•
Provides N times 8000 rates from 16,000 to 64,000 bits per second.
Application Example
The following is one example of how the Subrate LIM can be configured to operate with a
SpectraComm V.F 28.8 modem over a 2 wire private line at 24 kbps.
1. Subrate LIM Hard Options: S1 configuration settings for both the local and remote LIMs:
S1-1
S1-2
S1-3
S1-4
S1-5
S1-6
S1-7
S1-8
2. Subrate Clocking Configuration Parameters:
Clocking
Timing
3. Modem Commands: The following list of commands to the SpectraComm V.F 28.8 modems
are required. For other modem commands refer to SpectraComm V.F 28.8 Manual No.
060R112-000. If the switched network is to be used, the OCM shelves require that the
SpectraComm dual 8-position modular jack Zone 1 connector panel be installed. The top 8-
position modular jack connector is used for private line connections, and the bottom 8-position
modular jack connector is used for switched network lines.
Configuration Parameter
2-Wire Private Line
Synchronous Data
Speed (24 Kbps)
External Timing
Answer Mode
Retrain Disable
Store Configuration
These commands can also be sent as one command as shown below:
Originate
Answer
The modems connect together through a straight thru 8-position modular jack cable. The modems
can be placed in any unconfigured slot. The OCM 1000 Controller does not allow you to configure
the SpectraComm card. However, it will tell you if the slot is occupied.
4-16
ON
OFF
24 kbps
OFF
OFF
OFF
Nx rate = 8k
OFF
Nx rate
ON
Non-redundant
ON
Node Timing
internal
facility
node
2node
Originate
AT&L1
AT&M1
AT\T13
AT&X1
AT%Q0`
AT&W
"AT&L1&M1\T13&X1%Q0&W"
"AT&L1&M1\T13&X1%O1%Q0&W"
Office Connunications Manager OCM-1000/OCM-2000
Installation & Operation
Subrate LIM
Answer
AT&L1
AT&M1
AT\T13
AT&X1
AT%O1
AT%Q0
AT&T
036R340-000
Issue 16
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