How can convert variable-size signal ?

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.

[Walter Roberson]

What are the ADC blocks? They look like they are most likely to be analog to digital conversion, but analog to digital conversion requires finite time and so should be on a discrete clock instead of continuous time like you have now.

[Sarfaraz Ahmed]

Thanks sir. The ADC block is consist of customized MATLAB function block (through code) which generate only scalar value. I attached snap inside of ADC. Also I use pulse generation for clock. I attached snap also of clock. Please have a look and suggest how can I remove this error

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.

Please help in this regard. Thanks

[Walter Roberson]

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]

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;

Please have a look. Thanks