Fixed step size in a DC Motor Simulation

Hi all, i have a problem with my DC motor simulation, i have simulated that in xcos (it is like simulink by scilab) and yesterday i bought Matlab and when i attempted to simulate my dc motor, it failed.

In the following captchas you can see my simulation and parameters.

This is the error message

Derivative input 1 of 'DCMotorconparametros/Transfer Fcn4' at time 2.7 is Inf or NaN. Stopping simulation. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances)

And the warning message is:

"Warning: Unable to determine a fixed step size based on the sample times in the model 'DCMotorconparametros', because the model does not have any discrete sample times. Picking a fixed step size of (0.1) based on simulation start and stop times. You can disable this diagnostic by explicitly specifying a fixed step size in the Solver pane of the Configuration Parameters dialog box, or setting the 'Automatic solver parameter selection' diagnostic to 'none' in the Solver group on the Diagnostics pane of the Configuration Parameters dialog box. "

Captchas http://imageshack.us/photo/my-images/265/capturaua.png/

Thank's

[Chirag Gupta]

Try a smaller step size. Change the 'auto' to a value like 0.05

Answer 1

[Fangjun Jiang]

Your system is continuous. Try ode45 with variable step size first.

Answer 2

[Fernando Loyola]

Thank Fangjun for you answer, but i tried that and this was the result:

Warning: Using a default value of 0.1 for maximum step size. The simulation step size will be equal to or less than this value. You can disable this diagnostic by setting 'Automatic solver parameter selection' diagnostic to 'none' in the Diagnostics page of the configuration parameters dialog

[Fangjun Jiang]

This is a warning message. You can either ignore it, or set up the min and max step size in the "Configuration Parameters ..." dialog.

[Fernando Loyola]

very thanks :D