@Eric thank you for your answers. 
I have found one conversion example explained in here. However, what is this gain parameter? (you set it to 3 for Tanh in the example).
Normally the conventional Tanh starts from -1 to 1. The spiking one starts from 0 and then for few time steps it is 0 and then it starts going down towards -400 and starts behaving like Tanh in a spiking way. I this because it starts accumulating current in the start?
Now how would an input value be mapped? How would this mapping work? For instance, I have an input value of 1 it would be mapped to approx. to 0.77 in conventional Tanh. What about in spiking version? How would this mapping look like?
I am sorry if this question has been already answered on the forum.
Thank you for your answers.