¹⁴An example of a case where it is better for gain (K_p) to influence all three control modes is when a technician re-ranges a transmitter to have a larger or smaller span than before, and must re-tune the controller to maintain the same loop gain as before. If the controller’s PID equation takes the parallel form, the technician must adjust the P, I, and D tuning parameters proportionately. If the controller’s PID equation uses K_p as a factor in all three modes, the technician need only adjust K_p to re-stabilize the loop.