SBC PCD1.Room - Watchdog (Software)

Hardware Manual PCD1.M2110R1 │ Document 27-619 │ Version ENG 04 │ 2018-08-20
Saia-Burgess Controls AG
Watchdog (Software)
CPU / Control Process Unit
3-15
3
3.10 Watchdog(Software)
Thehardwarewatchdogo󰀨ersmaximumsecurity.Asoftwarewatchdogcan
besu󰀩cientfornon-criticalapplications,wherebytheprocessormonitorsitself
and the CPU is restarted in the event of a malfunction or a loop. The core of the
watchdog software is the instruction SYSWR K 1000. The watchdog function is
activatedwhenthisinstructionisoutputforthersttime.Itmustthenbeoutput
at least every 200 ms, otherwise the watchdog will be triggered and the PCD
restarted
InstructioninAWLcode:
Label Com-
mand
Operand Comment
SYSWR K 1000 ; Software watchdog instruction
R/K x ; Parameter according to the following
; table
; K = Constants or
; R = Register
; Blank space
; x = 0 The software watchdog is deacti-
; vated.
; x = 1 The Software Watchdog is activat-
; ed if the instruction is not
; repeated within 200 ms, a cold
; start is performed.
; x = 2 The Software Watchdog is activat
; ed if the instruction is not
; repeated within 200 ms, XOB 0 is
; called, then a cold start is
; performed.
“XOB0”callsareenteredinthePCDHistoryasfollows:
«XOB 0 WDOG START» if XOB 0 was triggered by the watchdog software
«XOB 0 START EXEC» if XOB 0 was triggered by a power supply error