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6.27 SVC_REQ 29: Read Elapsed Power Down Time
Use SVC_REQ 29 to read the amount of time elapsed between the last power-down and the most
recent power-up. If the watchdog timer expired before power-down, the CPU is not able to calculate
the power down elapsed time, so the time is set to 0.
This service request cannot be accessed from a C block.
This function has an output parameter block only. The parameter block has a length of three words.
Address
Power-down elapsed seconds (low order)
Address + 1
Power-down elapsed seconds (high order)
Address + 2
100µS ticks
The first two words are the power-down elapsed time in seconds. The last word is the number of
100 µs ticks in the current second.
Note: Although this request responds with a resolution of 100 µS, the actual accuracy is 1 second.
The battery-backed clock, which is used when the controller is powered down, is accurate to
within 1 second.
SVC_REQ 29 Example
When input %I0251 is ON, the elapsed power-down time is placed into the parameter block that
starts at %R0050. The output coil (%Q0001) is turned on.
%I0251
SVC_
REQ
CONST
FNC
00029
%R0050
PARM
GFK-2950C
Chapter 6. Service Request Function
February 2018
%Q0001
325
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