Interceptor RPM Signal Fault

[ToughDiesels]

Guys i am trying to install an interceptor onto an RD28ETI which is electronic control just like a petrol setup, has a MAF,TPS etc on nissan patrol diesel.
Now my issue is , i have a signal from the CAS going into the Analogue 1 input but no RPM reading on the laptop so cant do any mapping etc without it of course.

It seems pretty basic to setup but how does the Interceptor know what input i am using for the RPM signal and is there a way to dedicate each input to different parameters.

Thanks in advance.

MAtt