With firmware v1.16, the invert function is available in the channel menu.  If the unit has the older firmware v1.14 or below, the invert channel feature on the 5 or 6 series MSO is supported via the math channel instead. Here is the setup procedure: 1)  Click on "Add New Math" 2)  Select the Math Type to "Advanced" 3)  Put in INV(CH1) or click on the "Edit" button to select the invert function from the list