input range for usb6008 daq and pid controller

i used this code to acquire data but the maximum input voltage that the card could read was 10.4 volt on a3 however it is differential that is ranging from+20to -20 according to datasheet

also i want to use pid controller to output control signal u is this code correct? % ai = analoginput('nidaq', 'Dev1'); %Create an analog output object AO = analogoutput('nidaq','dev1'); addchannel(ai,0:3);

    %Add hardware channels to analog output object
    chans = addchannel(AO,0);
    % Set the SampleRate

    set(AO,'SampleRate',100)

    for ii = 1:40 %loop for aqcisition  
      start(ai)
    [data,time,abstime,events] = getdata(ai);
    plot(data);

fismat = readfis('CVfinalsm55') getfis(fismat);

Vref=evalfis([46;700 ],fismat); %Calculating the error

 for i=1:3
    read=getsample(ai)
    Vmeasured=read(:,4)
e(i)=  Vmeasured-Vref
end
IE=sum(e); %Integral of  Error

KP=20; KI =10; u=(KP*e+KI*IE) %pid

   for i=1:length(u)

        t = timer('TimerFcn', ' putsample(AO,u(i))',...
              'StartDelay',0);
        start(t)

    end
end
  end