Same output on multiple programs

Hi!

I have a problem related to using same output on multiple programs.

I have for example "Out1" in PLC1 Program and i need to use that same digital output in my another POU. But i dont know how i get both programs work to together with the same output.

Using CODESYS 3.5 enviroment

Thanks allready,
Joel

It is not exactly considered good practice, but you can easily access the same output multiple places.
Say you have Out1 AT Q*.
In Prg1 you set this to blink every 2 seconds, in Prg2 you set it to blink every 1 second.
Then you call either Prg1 or Prg2.


Keep in mind though, that the output will keep its last called state.
So if the output is high in Prg1 and you suddenly stop calling Prg1, then the output will remain high.

In serious programs (more complex than garage doors) it is not good practice to work directly with outputs.
Better practice is using some type of pre outputs instead, let's call it x_out_1 to x_out_n.
In the beginnig of the cycle init all these pre outputs to false (zero).
Now, different functions (or other parts of the program) can set some x_out to true (one) (be carefule, use SET or if (condition) then x_out = true).
At the end of the cycle write these pre outputs to outputs, out_1 = x_out_1 ..

Djuro

From another thread, my example mentions AOIs, but would be Function Blocks and Set/Reset in Codesys.

First of all. Declare your physical outputs always as a global variables. Then, use local variables in your pous and assign them to global vars elsewhere

I just ran across this, interesting

By output I have to assume that you are referring to remote outputs (Networked)
inputs and outputs in a base unit of a plc can only be accessed by that processor
As for remote I/O you would never want to control a output from more then one plc it could cause real problems.
Rockwell dos allow you read inputs from a remote input with multiple plc's but there is a limit on the number.
but they only allow 1 plc to control the outputs (Master)
You use produced and consumed I/O to pass info from the second plc to the master and program the master control the output as needed

By "Global variable" i mean variables which are declared in the global variable list in the project tree as a VAR_GLOBAL. Global variables are recognized throughout the project. "Local variables" are declared in the individual programs inside plc project. Physical I/O's are to be linked only to global_variables.

GaryS said:

By output I have to assume that you are referring to remote outputs (Networked)
inputs and outputs in a base unit of a plc can only be accessed by that processor

Click to expand...

Some Codesys based plc's like Beckhoff (Wago also?) doesn't include any I/O's in the "base plc". It's just a processor and all I/O cards are connected bus like Ethercat.

First off, I have never used codesys.

I have a customer that has a machine that has interchangeable assembly fixtures. they have the same valves.

we used 4 proxes to set up an id system to id the fixture.
we then had the main routine and multiple subroutines.
each subroutine defined an output BIT, not the physical output.
at the end of the program, we hade the physical outputs.
each cycle, all outputs had to be off and everything had to be in the home position before the accept / fail light would turn on a part sensor was used to reset the accept light and allow the next cycle to start.

hope this helps, james