How do i set watchdog in codesys?

kidi3 · Nov 16, 2016

I've currently set my PLC as a modbus slave, and written some python code which connect to it and act as a modbus client.

I am having some problems with the modbus server sometime terminating the PLC, when the python code request/send information to the slave.

It terminates by showing a popup window saying:

Code:

runtime error #16 (watchdog expired Task = default task)

And then a error message which it terminates with is:

Code:

IEC Task 0 ' cycle time is greater than the set watchdog timer; or cycle time exceeded, but shorter than watchdog timers

The only code I am running on the PLC is basically

Code:

(*Bit0 := TRUE;*)
    (*Bit1 := TRUE;*)
    (*Bit2 := TRUE;*)
    
    DO1 := Bit0; (* Start/Stop *)
    DO2 := Bit1; (* Direction [False - Reverse ; True - Forward] *)
    DO3 := Bit2; (* Speed [Fast = 11; Medium = 10; Slow = 01 ; Stop = 00] *)
    DO4 := Bit3; (* Speed [Fast = 11; Medium = 10; Slow = 01 ; Stop = 00] *)

and thats it. Bitx are coil address's and DOx are digital outputs on the PLC.

I guess, based on the error message it has something to do with the watchdog. I haven't manually changed anything with the watchdog, or even set it?..
How do I in codesys configure it?

bkottaras · Nov 16, 2016

Is it a periodic task?
Or are you using the watchdog system function anywhere?
I've attached a couple of screen shots.

kidi3 · Nov 16, 2016

Thanks for the reponse

Mine looks like this

Image

I can see the except_watchdog radio buttom, but i cannot press it. nothing happens to it.

The task is running constantly.. It just act as server that reads some coils and set some output pins based on the coil register values.
The coils values are being set by the modbus client in this case the python code.

--Edit--

I seem to be able to press the radio buttom now. Adding that radio buttom give me an error message:

Error 3569: POU for system event excpt_watchdog not defined

bkottaras · Nov 16, 2016

Click on "System Events" to fully expand the system events, it'll look the same.
Not sure what the python stuff does.

kidi3 · Nov 16, 2016

The python code act as modbus TCP client, and sets the coils which the server (PLC) reads from. Clicking on system events, shows the same screen as yours. But when i tick the "excpt_watchdog", and tries to compile the program I get an error message:

Error 3569: POU for system event excpt_watchdog not defined

bkottaras · Nov 16, 2016

You get the message because when you check mark the "watchdog" under events, you need to write a POU for that event.
Leave it as ii was originally (no check mark).
Not sure what the setup is but this is not your rproblem (the event "watchdog".
Can you run your program in a single step mode?
In Single step, the watchdog error , even if it exists will be set inactive.

bkottaras · Nov 16, 2016

I have codesys v2.3 and I'm using Wago hardware.
If you feel like it post your rpogram.
Someone can take a look at it.

kidi3 · Nov 16, 2016

The program in codesys is the litterally the code posted above.

Here is a dropbox link to the AC500 project
https://www.dropbox.com/sh/ft4p5me182qjcro/AABy2XjI2QukPsN90ZxWgICUa?dl=0

How do i run it in single-step mode => what is single step mode?

bkottaras · Nov 16, 2016

If you go online you have the option to run the actual program continiously or have breaks and even do a single step where you actually drive the program/scan.
Look under "Online" menu, it shoud be there.

bkottaras · Nov 16, 2016

Since you are using a Master/Slave, I'd look into that setup in order to figure out how/if the watchdog is setup.Open any configuration screens related to your network setup and look for it.
The dropbox location does not contain anything with the extension ".pro".
That's what I use to open the wago/codesys software I have.
I assume you use an ABB PLC?

kidi3 · Nov 16, 2016

You mean single cycle?

Nothing happens when i press it.

yes.. I am using ABB PLC..

It does have a modbusTCP server setup screen..

kidi3 · Nov 16, 2016

here is some PLC specific configuration.. but none seem to change them..

Highland Controls · Nov 16, 2016

Here is your project with a cyclic task and watchdog added. You can at least control the settings now and see what happens. FYI-your Modbus bits are going to step on your first Modbus word.
https://www.dropbox.com/s/tebb7kxz5op5zmt/Project2.project?dl=0

kidi3 · Nov 17, 2016

how should i open the project file?

Highland Controls · Nov 17, 2016

Just like you opened the original project file....

How do i set watchdog in codesys?

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