Chapter 2
Analog Input Timing/Control
©
National Instruments Corporation
2-69
DAQ-STC Technical Reference Manual
AI_SI_Q_St
bits: <9..10>
type: Read
in: AI_Status_2_Register
address: 5
This bitfield reflects the state of the SI control circuit:
0: WAIT 1.
1: CNT 1.
, for more information on the SI control circuit.
AI_SI_Reload_Mode
bits: <4..6>
type: Write
in: AI_Mode_2_Register
address: 13
This bitfield selects the reload mode for the SI counter:
0: No automatic change of the SI load register.
4: Alternate first period on every STOP. Use this setting to make the time interval
between the START trigger and the first sample pulse different from the remaining
sample intervals.
5: Switch load register on every STOP. Use this setting to synchronously change the
sample interval at each STOP.
6: Alternate first period on every SC_TC. Use this setting to make the interval between
the START1 trigger and the first scan different from the scan interval.
7: Switch load register on every SC_TC. Use this setting to synchronously change the
scan interval at each SC_TC.
AI_SI_Save_Value
bits: <0..7>
type: Read
in: AI_SI_Save_Registers
address: 64
bits: <0..15>
type: Read
in: AI_SI_Save_Registers
address: 65
This bitfield reflects the contents of the SI counter. Reading from this bitfield while the SI
counter is counting may result in an erroneous value. The eight MSBs are located at the lower
address and the 16 LSBs are located at the higher address.
AI_SI_Source_Polarity
bit: 4
type: Write
in: AI_Mode_1_Register
address: 12
This bit selects the active edge of the SI source (the signal that is selected by
AI_SI_Source_Select):
0: Rising edge.
1: Falling edge.
Set this bit to 0 if an internal timebase is used. Related bitfields: AI_SI_Source_Select.