The trigger coupling parameter can be either AC, DC, HF Reject, LF Reject, or AC Plus HF Reject. This parameter works much like the vertical coupling parameter. When AC is selected, NI-SCOPE rejects the DC component of the trigger signal. When triggering on channel 0 or channel 1 of the digitizer, the input signal is immediately coupled based on the vertical coupling parameter. Therefore, if the vertical coupling parameter is set to AC coupling, triggering occurs on the AC components of the signal because the DC component has already been removed.

Note   For the PXIe/PXI/PCI‑5122, trigger coupling applies only to the external trigger channel. When using the analog input channels (channels 0 and 1) as the trigger source, the trigger coupling is the same as the input coupling and is specified by calling Configure Vertical.