Measurement Computing UL for NI LabVIEW - Manual (Page 102)

Universal Library Virtual Instruments (VIs) Miscellaneous VIs
CurCount Specifies how many points have been input or output. It can be used to gauge how
far along the operation is towards completion. Generally the CurCount will return
the total number of samples collected at the time of the call to cbGetStatus() .
However, in cases where CONTINUOUS and BACKGROUND options are both set, the
way that CurCount behaves will depend on board type and transfer mode. This
value may recycle as the circular buffer recycles, or may continuously increment
with the number of counts transferred. Also,
CurCount may not update on each
sample. For example, when running in BLOCKIO mode, CurCount will update after
each packet of data has been transferred. The packet size is board dependent. Refer
to board-specific information for details.
CurIndex This is an index into the data buffer that points at the start of the last completed
channel scan. This can be used to provide a real- time display for a background
operation.
Data [ CurIndex ] points to the start of the last complete channel scan that
was put in or taken out of the buffer. You should expect CurIndex to increment by
the number of channels in the scan as well. If no points in the buffer have been
accessed yet then
CurIndex will equal -1. This value can also behave differently in
cases where CONTINUOUS and BACKGROUND options are both set (see CurCount
description). Refer to board-specific information for details.
If you use the CONVERTDATA option with either the CONTINUOUS option or with pre-
triggering functions then CurIndex will return the index of the last A/D sample,
rather than the start of the last completed channel scan.
For many background operations CurCount = CurIndex . For pre-trigger inputs
though, they are different. If the hardware allows background trigger operations,
CurCount indicates how many points of the TotalCount have been collected.
CurCount will rise to PreTrigCount , stop until the trigger occurs then rise to
TotalCount . CurIndex though will constantly increase and reset as it goes around
and around the circular buffer while waiting for the trigger to occur.
Data Array of acquired data or output data, depending on the background operation.
CurCount and CurIndex refer to this array.
ErrCode Error code returned from the Universal Library. Zero if no error occurred. Use the
ErrMsg VI to convert ErrCod e into a readable string.
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