General device configuration
DLT-V72 Operating Instructions V2.50 Preliminary
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8.5.
Automatic shut down
8.5.1.
Functional description
The DLT-V72 is equipped with an automatic shutdown module.
If wired up accordingly, the DLT-V72 conveniently switches off together with the vehicle’s ignition.
As disconnecting the power supply during operation can lead to data loss, the operating system needs
to be shut down normally using the appropriate hardware and software installed on the system when the
ignition is switched off.
The DLT-V72 is connected to the vehicle with three supply cables.
DC+ and DC- are directly connected to the power supply of the vehicle, the connection is of course run
through fuses.
The supply voltage connected is then linked to the DLT-V72’s ignition input via a switch, for example, the
key switch of the ignition (also with a fuse).
Sequence
When the vehicle ignition is turned on or the DLT-V72 <Power> button is pressed, the DLT-V72 checks
its internal temperature and runs a test to confirm that the automatic shutdown function is working.
If this check of the environmental conditions is successful, the DLT-V72 starts the operating system
normally.
Once these checks have been successfully completed, the DLT-V72 starts the operating system. No
environmental conditions (e.g. the internal temperature of the device or the state of the ignition input) are
checked for one minute during startup.
After one minute, the DLT-V72’s internal temperature and the state of the ignition input are constantly
monitored.
If the DLT-V72’s internal temperature reaches a critical level, a controlled shutdown of the operating
system is carried out. The computer will remain switched off until the temperature is once again within
the permitted range.
If the ignition input is
grounded or isolated during normal operation of the DLT-V72, the device will switch
to a delayed shut-off state.
The device will continue to operate normally in this state until the shut-off delay (e.g. 20 minutes) has
elapsed.
If the ignition is turned on again during this shut-off delay, the DLT-V72 will revert to a normal
operational state.
Once the shut-off delay (after run time) has elapsed, the operating system will shut down and the device
will automatically shut down (e.g. after one minute or a signal from the operating system).
Device shut down
If the operating system is shut down, all applications will be notified via the Windows message
“WM_QUERYENDSESSION” first.
Every application must then respond within the time set in the registry. If there is no response within the
preset time, the application will be hard-terminated.
It may not be possible to close an application automatically if it has unsaved data. Example: For
example, the WORDPAD.EXE program (included in Windows) cannot be closed automatically if there
are unsaved changes. In such a situation, WORDPAD.EXE will acknowledge the
“WM_QUERYENDSESSION” Windows message by prompting the user to choose whether to save or
not.
All applications that can be terminated without user confirmation using the keyboard shortcut <ALT> +
<F4> will normally also respond correctly to the “WM_QUERYENDSESSION” message and therefore do
not need to be hard-terminated.
