User's Manual

Chapter Three Configuration
Man_455U-D Rev 3.01 Page 47
3.9 Low Power Mode
The modem can be configured for low power shutdown when the DTR signal on the data
RS232 port is “reset”. In this state the supply current is reduced to approx 50% of normal load,
and the modem will not receive or transmit radio messages.
When in low-power shutdown mode, the OK Led flashes red-green at a 2Hz rate
(red 400 msec, green 100 msec).
This is configured in the Modem/General screen, or using
the AT&D Hayes command (AT&D3 to enable).
The use of this low power operation may be applicable in
remote locations where there is a limited power supply such
as solar panels. In this situation, the DTR signal from the
host device is used to “wake-up” the 455U-D unit. The
455U-D unit will then operate normally until the DTR
signal is reset by the host device.
In addition, the modem will go to low power mode if the
12V supply becomes too low. This feature is designed for
battery backup use. The 455U monitors its battery supply,
and if the battery voltage falls below 10.7 volts for more
than 5 seconds, the modem goes to low-power shutdown
state. The battery supply must rise back above 11.7 volts
before the modem will exit low-power shutdown mode.
If the modem shuts down because of low voltage, asserting
DTR at the RS-232 port will not cause the unit to “wake”.
The unit can be forced to normal operation from low power
shutdown by plugging a configuration cable to the CONFIG
port (with DTR line connected).
3.10 Optimum Path Routing
Optimum Path Routing (OPR) provides support for various host protocols. This mode uses
knowledge of the host frame format to ensure that a full packet of information is sent over the
radio in a single transmission. The host message is examined, and the destination address is
extracted from the message. This is used to look-up the protocol routing paths (AT&P
command configure these routing paths).
Optimum Path routing is available in firmware version 3.00 and later.