b) Using an S-function (either m-code or c-code). This has the advantage of having clearly defined bits of the code for initialization and termination. The termination part inparticular overcomes the above problem in using the EML block.
It does not behave like I expect. With other relevant posts, I want to define file handle 'fid' as persistent in Callbacks InitFcn to make file open only once at the beginning. But the error message shows that:
Error evaluating 'InitFcn' callback of block_diagram 'resp1'.
Caused by: A PERSISTENT declaration is only allowed in a M-file function.
When I remove the persistent fid definition to custom Matlab function, as:
function y = f_data_in() %#codegen % persistent fid; coder.extrinsic('fopen'); coder.extrinsic('fgetl'); coder.extrinsic('str2num'); % fid=fopen('x21A0.txt'); y = 0; y0 = zeros(1,3, 'double'); tline = fgetl(fid);
y0 = str2num(tline) y = y0(1,3); end
The tline will always be the first row data. It is not read each line by Simulink in every step as I wish.
I hope that each Simulink step reads one row data from the large file. In this way, no big computer memory requirement needs at all. Any one can help me on my question?