How to write the trial run of electrical, instrument and computer equipment?

Two-position control: dual valve positioning of combustion temperature controller "function allows two electric valves to be adjusted in one controller." Usually, one valve drives the furnace or hot gas inlet, and the other valve is the cooling damper. With this function, it is not necessary to connect the controller through an external positioner. The VP function can be used with or without a feedback potentiometer; VP can also be used with PID in any control channel to provide control strategies such as PID heating /VP cooling.