Multiple Serial Callback executions

Hello,

I have been working on a UI for some serial devices. The protocol is packet based.Every packet i receive consists of a header( 3 bytes) in which the length of the packet is defined. depending on this i read the rest bytes.

For this i use the BytesAvailable callback with a callback function in a separate mfile. Here is a snippet

Inside the callback of a button

    handles.s = serial('COM14');
    set(handles.s,'BaudRate',115200,'BytesAvailableFcnMode','byte',...
    'BytesAvailableFcnCount',3);
    set(handles.s,'BytesAvailableFcn', {@UI_DataCallback_Monitor,handles});

Inside the callback function

function UI_DataCallback_Monitor(obj,event,handles)
  header = fread(obj,3,'uint8');
  length=Uint8toUint16(header(2),header(3),0);
  data = fread(obj,length,'uint8');
  checksum=fread(obj,1,'uint8');

The problem is that as it seems multiple callbacks are being executed for every packet and results in timeout and errors.. I only want the callback to be executed once for each packet. Any suggestions?

Thank you