Hello,

I just started programming with CodeSys. Setup is an Exor etop513 and a Seneca ZC-24DI digital input module. I copied all can settings from a project that I know is reading the bus ok. I have a switch setup into input 9 where I want to latch the off - on transition. The switch is mapped into the PDO as Switch_Input1.

Here's the program:

PROGRAM Main
VAR
Enable_view: BOOL := FALSE;
Switch_on: BOOL := FALSE;
Switch_Count: INT := 0;
Switch_on_L: BOOL := 0;
END_VAR

Switch_on := Switch_Input1;
IF Switch_on = TRUE AND Switch_on_L = FALSE THEN
Switch_Count := Switch_Count + 1;
END_IF
Switch_on_L := Switch_on;

In Debug mode the switch is read correctly only once and then never changes. If I do a "Reset Warm" then the switch will be read correctly once again.

Any help would be greatly appreciated!

Is your IO value (Switch_Input1) refreshed correctly ?

Hi KMor77,

in your code you have the IF-clause

Zitat:
IF Switch_on = TRUE AND Switch_on_L = FALSE THEN

As the variables are defined as BOOL, you can say

IF Switch_on AND NOT Switch_on_L THEN

this will work too. But in general, your code looks ok. As dFx mentioned, the question is if your hardware comes in correctly. How is Switch_Input_1 refreshed on the bus? In the device-manager, on the Can-device Tab I/O Mapping you find a field "BusCycleOptions". Try here to select the task in which your program code is running.

Good luck
Alfred

Thanks for the response,

I've tried using Main Task and Parent bus cycle setting but neither worked.

The value is refreshed only once at the start of the program only.

I was under the impression that the bus continuously cycles and updates the I/O values according to the cycle period set in the manager.

Could it be a debugger problem?

That's strange

If you look in online status on the devices CANOpen I/O mapping, what happens with the Input Switch_input_1 when switching ON and OFF?

If nothing happens, try to remove your mapping variable and look if the status then is refreshed correctly...

Another stupid question: The code is called cyclical, not blocked by any condition?

Good luck

Alfred

Thanks Alfred,

I'll try that today and let you know what happens.

When you ask if the code is called cyclical that raises a question - My code is the main program and not called from anywhere. I thought the PLC just loops through the code Continuously.

Okay, that might be the problem!

In your project, you should see a "Task configuration". Double click the Task below that and you should get a window like this:

If the MAIN is not in the task, add it with drag and drop or by clicking "Add Call".
If you don't see a Task configuration below the application, you need to add one by right-clicking on Application and select "add object" and then "Task configuration".

Codesys is a task-based system. If you want your MAIN program to be called cyclical, you have to place it in a cyclic task. That's different to a PLC like Siemens, where you have an OB1, that is called by the system all the time.

Hope that helps... Good luck!

Alfred

Thanks - Yes I have all of that set up already so I thought the Main task would cycle every Interval Time (100ms in this case) - There's something subtle I'm missing but I won't get back to try anything until this afternoon.

Maybe the IO needs a sync signal to update the IOs and the CanOpen Master is not configured to send the sync telegram?

I have the CANopen manager set to "Enable Sync Producing" with a cycle period of 50 ms. Looks like I'm going to have to figure out how to go to a lower level to read the PDOs and/or find a diagnostic tool for the bus.