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P300H P300 Series Modem Installation and Operating Handbook Page 85
Back’ Alm 1234: [?] E=Ext A=Auto O=OK
1=EEEE 2=AEEE 3=AOOO 4=AAAA
Change, Tx/Rx, ESC/Aux/BA, Backward Alarm Menu
6.6.35 Change, Tx/Rx, ESC/Aux/BA, BACKWARD ALARMS Menu
This screen is used to configure the four backward alarm inputs used in multi-destinational IDR or for lower
rate multi-destinational operation in some of the Custom IBS modes.
This screen is at first difficult to understand, but is relatively simple. It allows the four backward alarm input
to be mapped in certain ways, without any external backward alarm patching:
On the screen the letters mean as follows:
E=Ext: External patch, the state from the backward alarm connector on the rear panel
connector will be sent (open circuit = OK, Ground = fail)
A=Auto: Auto, the alarm will be sourced internally from the summary Rx fail signal
O=OK: The alarm will always send the `OK` condition.
So the menu choices are as follows:
EEEE All four alarms report the state from the Backward Alarm connector on the rear
of the equipment . Use when transmitting a multidestinational carrier, but
where the carrier we are receiving does not correspond to the destination
allocated backward alarm channel 1. The Rx fail signals from the modems
receiving the carriers from all the other destinations (including this modems Rx fail
signal) must be externally patched into the corresponding external backward
alarm inputs.
AEEE Alarm 1 is internally connected to the Rx Fail signal, alarms 2-4 are available for
external patching. Use when this station is transmitting a multidestinational
carrier, where the carrier we are receiving corresponds to the destination
allocated backward alarm channel 1. The Rx fail signals from the other modems
receiving the carriers from all the other destinations must be externally patched
into the corresponding external backward alarm inputs 2-4. If the external inputs
2-4 are open circuit, then this is the same as AOOO below.
AOOO Alarm 1 is internally connected to the Rx Fail signal, alarms 2-4 always send the
OK state. Used in non multidestinational working, external backward alarm
inputs are ignored.
AAAA All four alarms represent the internal Rx Fail signal. Used in non
multidestinational working, external backward alarm inputs are ignored.
In non multidestinational operation, the choice between the third and fourth options is down to operator
preference or station policy.