Title: +038=360.000-OU045T_05-PCD2.m4160 PLS SBC - User Manual.pdf
PCD2.M4_ CPUs have a hardware watchdog as standard equipment. The watch- dog relay is at Pins 5 and 6 at Plug X4.Technical dataNumber of outputs Function Max. voltage Switching capacity1× relay switching contact Watchdog function or user output (selectable) 48 VAC or VDC 1 A (with DC switch-on voltage, a freewheeling diode should be con- nected in parallel to the load)Functional descriptionAs soon as the watchdog relay is called at the address O 255 by a switch on/ off frequency of < 200ms (or other value configured in device configurator), the  relay contact closes. It remains closed until the pulse time exceeds the configured  value.Example of an instruction list (IL) sequence:LabelCommand Operand CommentCOB0; or 1 … 150STL OUT OUTWD_Flag ; invert the help flag WD_Flag O 255; Output 255 blinkingECOBWith this code the watchdog triggers even for (continuous) loops that are due to  programming. Regarding user program cycle time, please note the following: