
TC1796
System Units (Vol. 1 of 2)
Watchdog Timer
User’s Manual
16-26
V2.0, 2007-07
WDT, V2.0
service sequence if all the expected paths and calculation routines have been executed
properly. If one or more steps were omitted or a wrong path was executed due to a
malfunction, the Watchdog failure mechanism will detect this and issue a reset of the
device (after the prewarning phase).
Figure 16-5 Monitoring Program Sequences
MCA05754
Determine branch
condition:
PW := A or B or C
Password access:
write xy
H
to WDTPW
Modify access:
set WDTPW to PW
Perform
Branch
Path B
...
...
PW := B
Return (PW)
Path A
...
...
PW := A
Return (PW)
Path C
...
...
PW := C
Return (PW)
WDTPW = PW
Next expected
Service
Sequence
n
Password access:
write PW to WDTPW
Modify access:
...
Service
Sequence
n + 1
Password is only correct if the
correct path was executed