how can i check if forward kinematic in a robotic arm is correct with a plot?

hi ,i hv made a robotic arm with 2 joint of freedom.i hv a webcam in the top of robotic arm and i hv write the forward kinematic in matlab (via matlab and arduino i want to make my robotic arm) and i want to check if x,y coordinates are correct in my robotic arm with a plot via camera... so can anyone know how to make a plot that shows if my robotic arm moves in correct coordinates???thanks