M7/M7L/M7LT Modular Satellite Modem Maintenance
M7/M7L/M7LT - Rev. 0.05 3-113
3.14.3. Operating 1:1 Redundancy Mode
Operation of a redundant pair of modems consists mainly of determining the status of units and
forcing transfer of operation from one unit to the other.
A quick status to determine which modem is currently on ”On-Line” and the failure state of the paired
modems is done by viewing the LED indicators on the front panels. In a fully operating set-up there
will be no alarms on either unit, but one modem will have the green Modulator Transmit LED
illuminated and the other will have the transmit LED extinguished. The other LED indicators still show
the relevant condition of the Modulator, Demodulator and Unit. A more thorough status condition is
viewed by setting both modems to the <Unit: Status – Redundancy> parameter.
The unit currently On-Line will present its status on the lower line of the LCD display as “Online –
xxxxx” where xxxxx could be one of several messages:
Bckup OK – The backup modem is not faulted
BCKUP ALM – The backup modem is in an alarm state
NO BCKUP – No backup modem was found via the aux communications channel
The unit currently Off-Line will present its status on the lower line of the LCD display as one of two
messages:
Standby OK – The offline modem is not faulted
OFFLINE – ALARM - The offline modem is in an alarm state
3.14.3.1. Manual Transfer Switch in 1:1 Redundancy Mode
The 1:1 transfer process of forcing the two paired modems to swap their on-line/off-line status is a
one step process. The procedure however can only be accomplished on the unit that is currently “On-
Line”.
On the currently “On-Line” unit go to the<Unit: Status – Redundancy> parameter and press the
“Edit” key.
The LCD display will present the message “Enter to Xsfer?”. Pressing the “enter key will cause
the unit to go off-line and the currently “Off-Line” backup unit to go “On-Line”.
NOTE: If there is no backup unit or the backup unit is in alarm then the transfer will not be completed
and an error message is displayed.
3.14.4. Removal and Replacement of Units in Redundancy Mode
It may be necessary to remove a unit of a redundant pair and replace that unit with another. The
following process performs that function with the minimum disruption to the traffic status.
1. Manually transfer the unit (if it is currently on-line) to the off-line position
2. Remove power from the off-line unit
3. Disconnection of cables from the off-line unit
4. Physical removal of the unit.
Replacement is the reverse of this procedure.
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