User`s guide

134
Troubleshooting Guidelines
Troubleshooting GPIB Interfaces
! The default formatted IO write buffer size is 128 so when using
this default size, formatted writes in SICL (with
hint =
I_HINT_DONTCARE
) and VISA (with VI_ATTR_DMA_ALLOW_EN =
VI_TRUE
) will used Polling mode even when a large number of
bytes are being sent.
! In SICL, Polling mode will always be used for the iread(),
ifread()
and iscanf() regardless of the above settings, when
a
termchr is set (itermchr() is not set to -1).
! In VISA, Polling mode will always be used for viRead(),
viBufRead() and viScanf() regardless of the above settings,
when
VI_ATTR_TERM_CHAR_EN = VI_TRUE.
The
crossover point at which the Interrupt mode becomes faster then the
Polling mode depends on the CPU speed, with a faster CPU having a higher
crossover point.