How to concatenate array of signal values in a for loop block in simulink with himself Indefinite number of times

trying to do the concatenation with for-loop block in simulink model using :

• for loop ietrator block (iterates for N loops (N=16 but can variate depends on other outside calculations))
• matrix concatenation block
• delay block

Each iteration get 1x4 binairy values as an array, as output from tghe subsystem reference block (here for example [1 0 1 1] )

this is repeated N = 6 times, each iteration will get different [x1 x2 x3 x4] array binary values, to be concatenated to previous ones ( [1 0 1 1 x1 x2 x3 x4] etc )

and so on until iteration n = 16 : we will get [ 1 0 1 1 ..... 1 0 0 1] a 1x16 binary values array

i get the error :

Unable to determine signal dimensions. There is a loop consisting of 'Hex2Bin_2022_Lab2/For Iterator Subsystem/Delay1' that cannot be resolved because signal dimensions are defined by a cyclic relationship

here is the snapshot of the model :

[Jon]

It's hard to figure out these dimensioning issues just from looking at a screen shot. Can you make a self contained example that reproduces the problem and attach it.

[Faouzi]

Number of iterations in for-loop is N variable (depends on input vector lenght: let say 1011 1110 1001 1111 0011 1100 )

so here N = 6

each input is 1x4 bits AND WE HAVE 6 INPUTS

the for-loop block is giving 1x4 output for each iteration like this

YYYY = f(XXXX)

where XXXX in 1011 1110 1001 1111 0011 1100

and YYYY is 1x4 bits respectivly for each XXXX combination

let say YYYY = 0101 in first iteration of the loop

than YYYY = 1111 for XXXX=1110

next YYYY = 1011

....

the last iteration ti gives YYYY = 0100

SO

the matrix concatenate here try to do this output :

010111111011....0100

1x24 bits

concatenation of all YYYY through all the for-loop outputs.

[Faouzi]

[Faouzi]

Answer 1

[Graham Cotgreave]

Had the same issue, resorted to the following, which is not much use for a larger number of values, but it did mean I could add a subsystem into the loop and get a vector answer.

It appears that the single Z-1 and a concatenator has the problem that it wants to concatonate at time zero, and not act like an empty FIFO as hoped.