On NI ELVIS II Family devices, APFI 0 and APFI 1 are not valid analog trigger sources. When using a Reference Trigger, supported trigger types are analog edge, analog window, and digital edge. When using a Start Trigger, digital edge is the only supported trigger type. Valid digital trigger sources are PFI 15 and SYNC terminals. NI ELVIS II+ also supports analog reference triggering with multiple channels for oscilloscope channels.