Saia-Burgess Controls AG
Manual PCD7.D412DTPF & PCD7.D4xxxT5F │ Document 27-620 – Release ENG07 │ 2019-06-20
3-17
Logic Controller
Software Watchdog | RIOs
3
3.6
Software Watchdog
The pWeb panels have a Software Watchdog, which is a self-monitoring function
of the pro-cessor which restarts the CPU in the event of a malfunction or loop. The
core of the Software Watchdog is the instruction SYSER K 1000. The first time this
is output, the Watchdog function is activated. This instruction must then be out
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put at least every 200 ms, otherwise the Watchdog is triggered and the controller
restarted.
Instruction:
SYSWR
K 1000 ; Software Watchdog instruction
R/K x
; Parameters according to following table
; K constant or entered value Register
x = 0
The Software Watchdog is deactivated
x = 1
The Software Watchdog is activated; if the instruction is not repeated within 200 ms,
a cold start is performed.
x = 2
The Software Watchdog is activated; 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:
«XOB0WDOGSTART» if XOB0 was triggered by the Software Watchdog
«XOB0STARTEXEC» if XOB0 was triggered by a supply fault
3.7 RIOs
Smart-RIO PCD3.T66x modules can be used for decentralised expansion via eth
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ernet (see also manual 26-892):