B&K Precision 2542B-GEN - Manual - Manual (Page 44)

Basic Operation
44
Fine Vertical Scale
Vertical Invert
Press CH2
→ More 1/2 → Invert to set Invert on or off. When
Invert is turned on, the voltage values of the displayed
waveform are inverted. Invert affects how a channel is
displayed, but does not affect triggering. If the oscilloscope is
set to trigger on a rising edge, it remains set to trigger on the
same edge after the channel is inverted.
Inverting a channel will also change the result of any math
function selected in the MATH menu or any measurement.