
DCW20
User Manual rev. 5
Page 11/34
3.1.5 PC shutdown and automatic restart
PC shutdown:
In case the DCW20 is used to supply a PC it is possible to automatically shut down
the PC after an adjustable time of backup. For this the PC must run the
POWERMASTER
application
(provided free) and must be connected through Modbus. Optionally
POWERMASTER
can call a task
on the PC before shutting down, for example to backup some sensitive data.
Automatic restart:
DCW20 is able to automatically restart a PC which was powered OFF by mistake,
for example in case of the Operating System (OS) crash. The user may adjust an output current
threshold and a timer used for detecting the PC OFF status. In order to restart the PC the DCW20
toggles the output OFF and then ON again. User must enable in the PC BIOS the automatic start in
case of supply ON.
The diagram below shows the DCW20 behavior when Shutdown and automatic restart is enabled.
Time
PC OFF signal
PC status
Output voltage
Output current
Input voltage
T1
T2
T3
...
...
T4 T3
E3
E1
E2
E4
Ioff
Figure 8: Shutdown and restart chart
Parameter Name
Description
E1
Backup
Power failure on the line happens. System enters backup
mode.
E2
Automatic PC
shutdown
The
POWERMASTER
sends a shutdown command to the PC.
Optionally: a task is called before shutdown.
E3
Unexpected PC
shutdown
The PC shutdowns in an unexpected way, for example caused
by OS crash.
E4
PC restart
DCW20 detects the PC being OFF because the output current
was lower than Ioff current threshold for T4 time. As a
consequence, DCW20 generates an ON->OFF->ON cycle on
its output.
T1
PC shutdown delay
User settable (§4.2.4). Time between start of backup and start
of PC shutdown procedure.
T2
PC shutdown time
User settable (§4.2.5). Time between start of shutdown
procedure and output voltage OFF. This time must be set
longer than the maximum time the PC takes to complete the
DCW20_040-02-700-005-EH-1117