National Instruments AT E Series - Manual (Page 161)

Appendix C Common Questions
© National Instruments Corporation C-9 AT E Series User Manual
acquisition completes. The above error occurs because NI-DAQ disarms
the counter from generating any more requests in the interrupt service
routine. Due to interrupt latencies, it is possible that the counter may have
generated some spurious requests which the DMA controller may not
satisfy because it has already transferred the required number of points.
What are the PFIs and how do I configure these lines?
PFIs are Programmable Function Inputs. These lines serve as connections
to virtually all internal timing signals.
If you are using NI-DAQ or LabWindows/CVI, use the Select_Signal
function to route internal signals to the I/O connector, route external signals
to internal timing sources, or tie internal timing signals together.
If you are using NI-DAQ with LabVIEW and you want to connect external
signal sources to the PFI lines, you can use AI Clock Config, AI Trigger
Config, AO Clock Config, AO Trigger and Gate Config, and Counter Set
Attribute advanced-level VIs to indicate which function the connected
signal serves. Use the Route Signal VI to enable the PFI lines to output
internal signals.
Caution If you enable a PFI line for output, do not connect any external signal source to it;
if you do, you can damage the device, the computer, and the connected equipment.
Table C-1. Signal Name Equivalencies
Hardware Signal
Name LabVIEW Route Signal NI-DAQ Select_Signal
TRIG1 AI Start Trigger ND_IN_START_TRIGGER
TRIG2 AI Stop Trigger ND_IN_STOP_TRIGGER
STARTSCAN AI Scan Start ND_IN_SCAN_START
SISOURCE — ND_IN_SCAN_CLOCK_TIMEBASE
CONVERT* AI Convert ND_IN_CONVERT
AIGATE — ND_IN_EXTERNAL_GATE
WFTRIG AO Start Trigger ND_OUT_START_TRIGGER
UPDATE* AO Update ND_OUT_UPDATE
UISOURCE — ND_OUT_UPDATE_CLOCK_TIMEBASE
AOGATE — ND_OUT_EXTERNAL_GATE