How to use Simscape language to create a rope / cable?

Hi,

i want to use the Simscape language to create a block that represents a cable / rope. In other words: If the length is the maximum length, pulling force is transmitted. Pushing force is never transmitted.

I tried this:

    equations
        if (eps > 0)
            f == (d^2/4*pi) * E * eps;
        else
            f == {0 'N'};
        end

        eps == ((l-l_0)/l_0);
        v   == l.der;

    end

But it is not working and there is always an error msg (Failed to update switched linear model, due to system singularity in current configuration.). Any ideas why? Thank you in advance!

[Lei Gao]

I have the same problem in SimMechanics when building up a model.

[john dent]

Same problem here too