How can convert variable-size signal ?

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Sarfaraz Ahmed 2018-11-12

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https://ww2.mathworks.cn/matlabcentral/answers/429338-how-can-convert-variable-size-signal

编辑： Sarfaraz Ahmed 2018-11-13

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Hi, I am getting this error in simulink. can anybody help how can be removed this error ? I only get this error when I attach switch with my ADC block. Also, I have attached the design snap.

The signal at input port 1 of 'ADC_Sign_E_ref_12/Switch2' is a variable-size signal with a nondiscrete sample time. The sample time for any variable-size signal must be discrete.

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Walter Roberson 2018-11-12

When a MATLAB Function Block is used, Simulink would tend to assume that the output is variable length. I would not count on the analyzer being able to prove that the output will be scalar: I would recommend configuring the output port.

Also can you post the code so we can see if there is an accidental variable length output path?

Sarfaraz Ahmed 2018-11-12

编辑：Sarfaraz Ahmed 2018-11-13

在 MATLAB Online 中打开

ADC_Sign_E_ref_12.mdl

Yes sir. I can list code here also I have attached the model. So when you run the model you will see that error and it would be easy to diagnose. I think also it's configuring issue. But I don't know how to configure the output port.

here Vin, Vip are the sampler values.

ADC code:

function y  = ADC(Vin, Vip)
coder.extrinsic('stem');
coder.extrinsic('get_param') 
sim_t=get_param('ADC_Sign_E_ref_12','SimulationTime')
Nbit = 7; 
Vref = 64;
%     generating empty plot
ax1=subplot(2,2,([3,4]));
ax2=subplot(2,2,([3,4]));
axis ([ax1 ax2], [0 0.2 -64 64]);
title('Dout Scaler Value');
xlabel('Time(s)');
ylabel('Amplitude');
hold on;
persistent Dout;
if isempty(Dout)
    Dout = zeros(1,2);
end
persistent B;
if isempty(B)
  B = zeros(1,Nbit);
end
% Conventional Set-and-Down SAR ADC
% 64C, 32C, 16C, 8C, 4C, 2C, C, C        
            Vxp = Vip;
            Vxn = Vin;
            for kbit = 1:Nbit
                if Vxp - Vxn > 0
                    B(kbit) = 1;
                    Vxp = Vxp - Vref*2^(-kbit);
                else
                    B(kbit) = 0;
                    Vxn = Vxn - Vref*2^(-kbit);
                end
            end
            Dout = B(1)*64 + B(2)*32 + B(3)*16 + B(4)*8 + B(5)*4 + B(6)*2 + B(7)*1 -64 +0.5 ;
            stem(sim_t,Dout);
            hold on;              
     y = Dout;

The control signal of switch is coming from below cnt block. The control signal either 0 or 1.

cnt block code:

function y  = clk(ip1)
persistent x; 
persistent i; 
persistent cnt; 
persistent out; 
if isempty(x)   % Initialization
  x=1;
end
if isempty(out)   % Initialization
  out=1;
end
if isempty(cnt)   % Initialization
  cnt=1;
end
if isempty(i)   % Initialization
  i=0;
end
while i>=0
    cnt = ip1+i;
    i=i+1;
    break
end
if cnt ==x
    out=1;
    x=x+4;
else if cnt~=x
        out=0;
    end
end
y=out;