Hi,

I'm fairly new to this and i have been struggeling with something for a few days now.
I searched the forum for similar cases, but could not find anything. The closest i found was this thread ( l viewtopic.php?t=1725 l ). Tried something similar with Pointer to Bool instead of Int, but that didn't work

I want to create an array of pointers to my boolean outputs. It shouldnt be so complicated but for some reason i'm not able to get it working.

The application is basically a learning program. I want to trigger inputs and save them in the order they are triggered. This should then be mapped to the corresponding outputs.
I.e. pseudo code arrayin[1]= input1 at%ix0.0, arrayin[2] = input2 at%ix0.1
That is then mapped to output arrayout[1] = output1 at%qx0.0 arrayout[2] = output2 at%qx0.1
Very simple and straight forward in my head.

However, every way i have tested it it either becomes a programming error (cannot convert pointer to bool sort of) or that the pointer "doesnt work".

Tested creating a standard array of bool and added output1 and output2 to it, when i then try to activate one of them (just arrayout[1]:=TRUE;) it gives the True value to arrayout[1] but not the adress for output1. Thats why i thought i must need an array of pointers (which point to my outputs/inputs).

I hope atleast someone understands what i mean..

Thanks in advance, br Chris

why use pointers?

just say output0:= outputarray[0];
output1:=outputarray[1];
etc.
pointers can be used but make the program only possible on one type of controller.
in the GLOBAL VAR list just say output0 at %QX0.0:BOOL;
etc
you can also do this in the PLC config but this is easier. and will print in your program.

Hi,

Sorry for my late reply.
The reason i started thinking of using pointers was that i could not get my program to work as i wanted.

However, when i tested what you wrote
output0:= outputarray[0];
output1:=outputarray[1];

tested by
outputarray[0]:=1;
(gave output0 = true)

that worked. but what i wrote originally was
outputarray[0]:=output0;
and
outputarray[0]:=1;
(did not give output0 = true)
And i could not understand why it didnt work.. To be frank, I still dont understand why the inverted declaration (as in yours') works but not mine.
I feel i have missed something basic with this. If you got the time i would be very grateful if you could explain it.

Thanks a lot.

br

outputarray[0]:=output0;
this will write the state of the output in the array
and
outputarray[0]:=1;
this will put a 1 in the array.

nowhere you say output0:= ????

and sorry chris in your first post the sequence was wrong ( i did not see this as it was all in one line.

Hi

outputarray[0]:=output0;
this will write the state of the output in the array
and
outputarray[0]:=1;
this will put a 1 in the array.

nowhere you say output0:= ????

=> outputarray[0] = 1 (array memory of position 0 = 1)

Ah ok. So with the inverse;
output0:=outputarray[0];
and
outputarray[0]:=1;
=> output0 (@qx0.0) = 1 (true/high)
And here write the state of the array to the output..

is connecting the array with the adress of the output0. That was what i was after, connecting the output adress to the array.
I thought it would work either way.

This atleast solved that problem and i think i understand the difference how Codesys handles local-/temporary memory and in/output adresses. I just need to keep track of how i want it to function.

Thanks again, br

a direct connect with an array is impossible, you can NOT make
VAR
arrayoutput[0] at QX0.0 :BOOL;
etc
END_VAR

but you can write a complete word from array to the outputs

VAR
maxarrays is ie 5
arrayout [maxarrays] array of word;
arrayoutput [maxarrays,16] of BOOL;
output0 AT QW0:WORD;
output1 ATQW1:WORD;
etc
END_VAR

in program you make
a loop with
for B = 1 to maxarrays
arrayout[B]:=0; // empty the counter
for A = 0 to 16
arrayout[B]:= arrayout[B]+ (arrayoutput[B,A]*EXPT(2,A)) // if output in array is TRUE (1) then add 2 power A
//
next A
next B
now they are in words
then
output0 := arrayout[0];
etc
this is all straight forward without any pointers, so very flexible and can be used on any type of PLC.

in util.lib there is
EXTRACT(in,n)
The n-th bit of DWORD in is returned in BOOl

PACK
Up to 8 bits are packed into a byte

PUTBIT
A bit of a DWORD is set to a certain value

UNPACK
A Byte is returned as single bits

for the rest of this have a look at w www.oscat.de w (also english version available.
get the lib, the pdf and the txt version.