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how to invoke soft watchdog trip?


windell747
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To create a foreground failure, the easiest way is to set Sys.RtIntPeriod to a very large value (say, 1000). You should quickly see Sys.WDTFault set to 2 (RtFault).

 

To create a background failure, I like to create a very long program as Brad suggests. I would create a program line with multiple I/O accesses (which take time) and some math, then copy this many times in the program. For example:

 

M1=sin(M2)+exp(M3)-cosh(M4)

 

where M1, M2, M3, and M4 point to I/O, not memory registers. You can combine this with the following trick:

 

open plc 5

Ldata.GoBack=10000; // Permit looping 10K times before exiting

while (P1==0) {

M1=sin(M2)+exp(M3)-cosh(M4);

...

}

close

 

You could also set Sys.WDTReset to 100 to make this as sensitive as possible.

 

You should see Sys.WDTFault set to 1 (BgFault).

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  • 2 years later...

Hi All

 

sorry for resuming an old thread, but I don't find any newer information on the topic.

 

To create a foreground failure, the easiest way is to set Sys.RtIntPeriod to a very large value (say, 1000). You should quickly see Sys.WDTFault set to 2 (RtFault).

 

I have a strange behavior on my Power Brick LV-IMS. Basically, after 3 / 4 hours of uptime, the PMAC trip a RtFault.

It is really strange becaue it trips after few hours of system alive, without any motion or action.

 

The PMAC is moving an Hexapod; kinematics have been written as C RealTime routines. The inverse kinematic is linear, while the inverse kinematics is an iterative loop that takes 3 to 5 iteration to solve.

 

The PMAC is continuously running 3 PLCs:

- PLC2 is the remote interface, waiting for remote commands; maximum execution time is around 6 us; Task Manager indicates a background cpu usage of < 1 % when this is active

 

- PLC2 is a state machine that, based on internal variables, set the status of some other global variables. Maximum execution time is around 20 us; background cpu usage is < 3 %

 

- PLC3 is the forward kinematics computation: it constantly ask the system dread, pread and tread, and then set some other global variables to be reported to the remote user. Maximum execution time is around 170 us and background cpu usage is ~14 %.

 

I think the origin of the RTFault is PLC3, that continuously asks forward kinematics computation; what I do not understand is why this is tripping even when the system is stopped, so the forward kinematics is not getting any strange values but the execution time shall be more or less constant.

 

Any ideas?

 

Thanks a lot

gigi

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