The DH-BVL-797W is a license plate capture camera and has a dual day and night mode for shutter speed variation. The day/night modes are configured by using dip switches located on the underside of the camera. The dip switch configuration information is located in the camera's product manual. To turn OFF the dual mode (activate IRs at night), switch all the dip switches to OFF.
If using an older model of the 797W, there is an internal modification that must be done to put the camera in long range IR mode. Please contact technical support if dip switch modification does not activate the camera IRs.