How can I specify a serial terminator > 127?

I am implementing serial communications specified in ICOM Communications Interface - V ver 3.2. I do not get an error number.

Each CI-V message begins with 'FEFE' [254 254] and terminates with 'FD' (253). Actual serial communications is in decimal. A typical message would look like:

['FE';'FE';'E1';'E0';'03';'FD'] or

[254
254
225
224
  3
253] as actually transmitted.

Is there a way to specify a 253 ('FD') terminator? If not, can you suggest a method to have the BytesAvailableFcn trigger on the 253 ['FD']?

serial object specified in Methods:

obj.serialObj = serial(obj.serialPort,...
     'BaudRate',19200,...
     'Parity','None',...
     'StopBits',2,...
     'FlowControl','None',...
     'BytesAvailableFcn',{@rfcPerseusRead,obj},...
     'BytesAvailableFcnMode','byte',...
     'BytesAvailableFcnCount',1,...
     'TimeOut',3,...
     'Name',['SDR-Serial-',obj.serialPort],...
     'Tag','perseusSerialObj') ;

Right now I accumulate the message response byte-by-byte:

function rfcPerseusRead(scr,~,obj)
ba = get(obj.serialObj,'BytesAvailable') ;
try
    while ba > 0
    dataDecimal = fread(obj.serialObj,1,'uint8') ;
    obj.dataMsg = [obj.dataMsg,dec2hex(dataDecimal,2)] ;
    ba = get(obj.serialObj,'BytesAvailable') ;
    end
catch
    try
        while ba > 0
             dataDecimal = fread(obj.serialObj,1,'uint8') ;
             obj.dataMsg = [obj.dataMsg,dec2hex(dataDecimal,2)] ;
             ba = get(obj.serialObj,'BytesAvailable') ;
        end
    catch
        'disp('Read Error') ;
    end
end
end

[cr]

Matlab allows only 0-127 for terminator character. Is the number of output bytes 6 per communication? If that is the case, increment your 'BytesAvailableFcnCount' to a multiple of 6. In the callback function extract the 3,4,5 bytes of interest.