I am using Julia 0.5.2

I am modeling a continuous time RLC circuit in the s domain. I am modeling a digital controller in the z domain.

I tried multiplying the 2 transfer functions together to get the open loop transfer function, but I get this message:

*Sampling time mismatch*

*in *(::ControlSystems.TransferFunction{ControlSystems.SisoRational}, ::ControlSystems.TransferFunction{ControlSystems.SisoRational}) at /home/venkat/.julia/v0.5/ControlSystems/src/types/transferfunction.jl:437*

_ in *(::ControlSystems.TransferFunction{ControlSystems.SisoRational}, ::ControlSystems.TransferFunction{ControlSystems.SisoRational}, ::ControlSystems.TransferFunction{ControlSystems.SisoRational}) at ./operators.jl:138_

_ in include_string(::String, ::String) at ./loading.jl:441_

How do we work in both the domains? Do I have to convert my z domain transfer functions to s domain, by bilinear transform?

any advice is appreciated.

PS: I guess I can use the c2d function to convert the continuous to discrete. But, I feel that we always lose something in conversion. Ideally, continuous and discrete transfer functions should coexist.