Thanks both of you for the replay,
I have seen the post that Luc have said me and I have one problem.
The code of my TF is:
> import hbp_nrp_cle.tf_framework as nrp
> def print_membrane_potential(t):
> return True
and I have the next error:
"field data must be of type str (runtime)"
I haven't found the error in my code. Does someone know what this error is due to?