Chapter 2
Analog Input Timing/Control
©
National Instruments Corporation
2-67
DAQ-STC Technical Reference Manual
AI_SHIFTIN_Polarity
bit: 12
type: Write
in: AI_Personal_Register
address: 77
This bit selects the polarity of the AI_FIFO_SHIFTIN output signal:
0: Active low.
1: Active high.
AI_SHIFTIN_Pulse_Width
bit: 15
type: Write
in: AI_Personal_Register
address: 77
This bit determines the pulsewidth of the SHIFTIN and AI_FIFO_SHIFTIN output signals:
0: 0.5–1.5 AI_OUT_TIMEBASE periods.
1: 1.5–2 AI_OUT_TIMEBASE periods.
The leading edge of the SHIFTIN and AI_FIFO_SHIFTIN pulses occurs immediately after
the active edge of EOC.
AI_SI_Arm
bit: 10
type: Strobe
in: AI_Command_1_Register
address: 8
Setting this bit to 1 arms the SI counter. The counter remains armed (and the bit remains set)
until it is disarmed, either by hardware or by setting AI_Disarm to 1. Related bitfields:
AI_SI_Armed_St, AI_Disarm.
AI_SI_Armed_St
bit: 5
type: Read
in: AI_Status_2_Register
address: 5
This bit indicates whether the SI counter is armed:
0: Disarmed
1: Armed
Related bitfields: AI_SI_Arm.
AI_SI_Count_Enabled_St
bit: 8
type: Read
in: AI_Status_2_Register
address: 5
If the SI counter is armed, this bit indicates whether the SI counter is enabled to count:
0: No.
1: Yes.
If the SI counter is disarmed, this bit should be ignored.