I need to simulate wheatstone bridge for 2 variable resistors at the same time but program simulated firstly one of them and the other after that.I want all of them in a step.What should i do? I upload the spice file.

Thank you.

 

You can set the value of a resistor to be variable, e.g it could be a function of some varying voltage.

 

Use this one step function: " .step param R 500 1000 10".
Then make one set of resistors {R} and the other set {1500-R}.
Thus {R} will step from 500 to 1000 and {1500-R} will step from 1000 to 500 at the same time.
Edit: See demo simulation below showing step change in resistance for two resistors.