SBC PCD1 Series User Manual

Saia-Burgess Controls AG
Manual Manual PCD 1 / PCD 2 Series │ Document 26 / 737 EN22 │ 2013-11-26
CPUs and expansion housings
3-57
Monitoring the CPU (watchdog)
3
3.19.2 PCD2 hardware watchdog
PCD2CPUsarettedwithahardwarewatchdogasstandard.ArelayatI/Oaddress
255 can be triggered; this remains activated as long as the status of O 255 changes
periodicallyatleastevery200ms.WithinPG5,FBoxesareprovidedforthispurpose.
IfforanyreasontheprogramcomponentwiththewatchdogFBoxisnolongerbe-
ingprocessedatsufcientlyshortintervals,thewatchdogrelaywilldropoutandthe
yellowwatchdogLEDwillgoout.Pleasereadonlinehelpformoredetailsonthese
FBoxes.
ThesamefunctioncanalsobeimplementedwithIL(AWL)instructions.Thereare
various ways of doing this:
Example:
 COB 0 ;or1 … 15
0
 STL WD_Flag ;Inverthelpag
 OUT WD_Flag
 OUT O255 ;Setoutput255toashing
: :
: :
ECOB
Withthecodeshowninexample,thewatchdogdropsoutinthecaseofloopscaused
bytheprogrammer.Withregardtothecycletimeoftheuserprogram,pleasenote:
● Withcycletimesofmorethan200ms,thecodesequencemustbere-
peated several times in the user program, to prevent a drop-out of the watchdog in
normal operation.
 Asaddress255isinthenormalI/Orange,therearerestrictionsonthepermissible
I/Omodulesincertainsockets:
CPU type Restrictions
PCD2.M110 none
PCD2.M120/M150 1) No analogue, counter and motion control modules on the
socket with base address 240
2) Output255cannotbeusedfordigitalI/Omoduleseither
PCD2.M170 1) No analogue, counter and motion control modules on the
socketswithbaseaddresses240and496
2) Outputs255and511cannotbeusedfordigitalI/Omodules
either
PCD2.M480 1) No analogue, counter and motion control modules on the
socket with base address 240
2) Output255cannotbeusedfordigitalI/Omoduleseither
Thestatusofthewatchdogisdisplayedbytheyellow"WD"LED:
● LEDlitup: Relayclosed
● LEDnotlitup: Relaydroppedout

SBC PCD1 Series Specifications

General

Brand	SBC
Model	PCD1 Series
Category	Controller
Language	English