Reading multiple signed digits from serial port

I'm using simulink support package for arduino to read serial data from port2 in Arduino due. My plan is to read signed integers (-415 for example) representing motor speed and feed it to the pid controllers as in the image.

from the far end i'm sending delimited data in the following shape . The matlab function in sumlink is supposed to read the received ASCII characters and add them to a variable until it reaches the end character '>'. I'm using the following simple code just to give the output on both the Right and Left to check if I'm receiving the correct data, However I'm not.

function [Right ,Left] = fcn(data,status)

 SON = '<';
 EON = '>';

 persistent receivedNumber;
 receivedNumber = 0;

 persistent negative;
 negative = false;

 if(status ==1)

    switch(data)

    case EON
        if (negative)
            receivedNumber = -1*receivedNumber;

        else
            receivedNumber = 1*receivedNumber;
        end

    case SON
        receivedNumber = 0;
        negative = false;

    case {'0','1','2','3','4','5','6','7','8','9'}
        receivedNumber = 10*receivedNumber;
        receivedNumber = receivedNumber + double((data - 48));

    case '-'
        negative = true;  

    end       

 end

    Right = receivedNumber;
    Left = receivedNumber;

 end

Can anybody tells if there are any other approaches to read multiple signed digits in simulink? Taking into consideration that I have to use the support package for Arduino since my pid controllers are already configured in Simulink and interfaced with port2 in Arduino (which will be connected to BeagleBone black)