Good time of day.

Please tell me a possible solution to the problem. There is an industrial oven with a modulated gas burner. The power of the burner is regulated by an electric drive. Accordingly, the burner has two inputs for regulation, the input is more gas and the input is less gas. There is a Siemens logo 8, a temperature sensor in the furnace and an electric drive of the burner flap (more/less).

How do I control this burner in PI law using discrete outputs? 

Oh, this is just amazing! I like how it works.

Is it possible to make the impact (less/more) triggered earlier, and not when the measured value passes through the setpoint?

My oven is very inertial and I want the controller to reduce and increase the gas supply in advance.