Saia-Burgess Controls AG
PCD7.D443WTxRx | Document 27-644 | Version ENG04 | 2017-10-30
20
Software watchdog (PCD7.D443WT5Rx)
The PCD7.D443WT5R panels have a software watchdog where the processor monitors itself and
the CPU is restarted in the event of a malfunction or a loop. The core of the software watchdogs is
the instruction SYSWR K 1000. When this is output for the first time, the watchdog function will be
enabled. This instruction must then be output at least every 200 ms, otherwise the watchdog will be
triggered and the controller restarted.
Instruction:
SYSWR
K
1000
; Function «Software Watchdog»
K/R x
; Parameter as per the following table
; K = Constante (0..16535) or R = Register contents
; 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
will take place.
; x = 2
The «Software Watchdog» is activated.
If the instruction is not repeated within 200 ms, XOB 0 will
be called up and a cold start will then take place.
XOB 0 call-ups are entered in the PCD history as follows:
"XOB 0 WDOG START"
if XOB 0 was triggered by the software watchdog
"XOB 0 START EXEC"
if XOB 0 was triggered by a supply fault
Also available as an F-Box
Connecting RIOs to the PCD7.D443WT5Rx
For decentralized expansion via Ethernet, the PCD3 Smart-RIO T66x modules can be used (see
also Manual 26-892)
For decentralized expansion via RS-485, the PCD1 RIOs can be used.
