What does "The last entry in tspan must be different from the first entry" mean?

Hello,

I developed a model in simulink in which instead of using the integrator block, I am using the Interpreted MATLAB function block and calling the ode "manually" from it.

Within the block I have the function:

ode15s(@(t,y) FcnSys(u(1),u(2),u(4),u(5),u(6)),[0 u(7)],u(3),'RelTol',u(9),'AbsTol',u(8),'MaxStep',u(10))

Where the input u(7) is the tspan desired. However, if I try to run this I get the error: "The last entry in tspan must be different from the first entry".

I do not quite understand why is this happening since u(7) is an input of the block. I set it to 50, so how come the entries are the same?

Can anyone help out please? I am struggling with this for a while now.

Thank you very much.

Sincerely.