Chapter 2 Analog Input Timing/Control©National Instruments Corporation2-113DAQ-STC Technical Reference Manual2.8.1 Internal Signals and OperationTable 2-9 describes the internal signals shown in Figure 2-44.Table 2-9. Internal SignalsSignal DescriptionAD_START Output Version of START—The hardware generates this signal bypassing the output of the AI_START selector through polarity selection,edge detection, synchronization, and additional circuitry that guaranteesthat AD_START pulses only when the START is recognized as valid bythe internal control circuits.AD_START1 Output Version of START1—This signal can come from two sources.If AI_Delayed_START1 = 0, the hardware generates AD_START1by passing the output of the AI_START1 selector through polarityselection and edge detection, but not synchronization. IfAI_Delayed_START1 = 1, AD_START1 is the same as ADR_START1.Related bitfields: AI_Delayed_START1.ADR_START1 Internal START1 Signal without Master/Slave Synchronization—Thissignal is generated by the hardware by passing the output of theAI_START1 selector through polarity selection, edge detection, andsynchronization (synchronized to FSC_SRC), bypassing master/slavesynchronization.ADR_START2 START2 without Master/Slave Synchronization—This signal isgenerated by the hardware by passing the output of the AI_START2selector through polarity selection, edge detection and synchronization,bypassing master/slave synchronization.AD_VSTART2 Output Version of START2—This signal can come from two sources. IfAI_Delayed_START2 = 0, then the hardware generates AD_VSTART2by passing the output of the AI_START2 selector through polarityselection, but not edge detection or synchronization. IfAI_Delayed_START2 = 1, then AD_VSTART2 is the same asADR_START2. Related bitfields: AI_Delayed_START2.AIERROR AI Error—This signal indicates that an analog error has occurred.AIFIFOREQ AI FIFO Request— This signal generates AIFREQ.AI_IN_TIMEBASE1 Internal Timebase for the Analog Input Module—This signal can beselected to be the same as IN_TIMEBASE, or it can be IN_TIMEBASEdivided by two. Related bitfields: AI_Source_Divide_By_2.
