I have problem with saving numerica variable.

I know J1939.Transmission.Output Shaft Speed from CAN
and some constant - PI , Radius of Wheel and Reduction Coefficient.

I need to calculated Car's Speed using formula:

Car.Speed = 2*Pi*R*Output_Speed*0.06/CoefRed

I've created new variable and set Fire on change "calculated speed" where
"calculated speed" is calculations event:

2*PI*R*0.06*J1939.Transmission.Output Shaft Speed / CoefRed

But value of my variable is zero all times.

Nikolay