NMX920 OEM Integrators Guide
Page 10 of 21
6. Modes Of Operation
The NMX920 is a microprocessor controlled, hybrid electronic device with special
requirements for power quality and application. The NMX920 is designed to operate with
power applied to the
External Interface
at all times, and provides the ability to power
itself on and off under software and hardware control. Because of the nature of radio
transmissions, and the MOBITEX network, the NMX920 needs to be able to control its
own powering down to ensure that certain time–critical processes are completed and the
system is left in a known state. If possible, OEM designers should provide for this
behaviour by powering the NMX920 from a constant power source, or the same source
as the OEM equipment.
IMPORTANT!
Care should be taken not to remove power from the External
Interface without properly shutting down the NMX920 via the
MASC FO command. For further information see section “Power
Sequencing”
If power is removed from the
External Interface
, without correctly shutting down the
NMX920, the MOBITEX network will become unaware of the modem’s Active/Inactive
state. This situation is recoverable, however the sudden loss of power could result in loss
of buffered messages. This section outlines the procedures necessary to properly power
and control the NMX920.
The following diagram outlines the relationship between the three power modes and the
mechanisms for changing between them.
The NMX920 operates in one of three distinct power modes while power is applied to the
External Interface
;
POWER-OFF MODE
,
BATTERY SAVE MODE
and
EXPRESS
MODE
. To provide control over the operational state, and power consumption of the
NMX920, the OEM can change between these modes by issuing certain MASC
commands and/or electrically activating the
DTR
line on the
External Interface
.
NO
POWER
POWER-OFF
MODE
Removal
of power
BATTERY
SAVE MODE
EXPRESS
MODE
Mode
change
Mode
change
Shutdown
"Power-on
request"
Application
of power
Network Contact
Operational
Shutdown
"Power-on
request"
