However, an X-Y graph is simply a MATLAB figure window, so assuming the block is open then the following will work
>> hf = findall(0,'Name',get_param(gcb,'Name')); %handle to figure window
>> ha = findall(hf,'Type','axes'); %handle to axis
>> set(ha,'XGrid','on','YGrid','on') % trun the grid on
Phil.
i also found it works!!
great
thanks