Error occurred in 'model_wor​k_with_mot​or/Control​ler Node/Regulator Node'. Error using getOutport​SampleTime​Ratio Reported by system.Ser​ialConfigu​ration: Incorrect number of out

I'm trying to use Simulink with arduino to control the position of a dc motor with an external pulse encoder over a network using truetime functions. the motor is connected to one arduino while the encoder to another problem is when im trying to use serial communication block i get the above error