x = zeros(4, 101); %Preallocation is much faster
Px = gObjects(1, 4);
for c = 1:4 %Initilize all your plots, for 4 pins
Px(c) = plot(handles.(['axes' num2str(c)]), 0, 'LineWidth', 2); %Store your plot handles
grid on;
end
for k = 2:101 %Did k to 101 since it looks like you want to keep the 1st point as a 0
for c = 1:4
x(c, k) = readVoltage(a, ['A' num2str(c)]);
set(Px(c), 'XData', 1:k, 'YData', x(c, 1:k)); %Setting the XData and YData directly to prevent redrawing plot from scrap.
end
drawnow; %Do only 1 drawnow, instead of 4 drawnow you had before
end
Note that instead of 4 plots, you could just have 1 plot with 4 lines for a little extra speed and simplicity in GUI.
