2Troubleshooting Guidelines
•The default formatted IO read buffer size is 4096 so when using
this default size, formatted reads in SICL (with hint = I_HINT_DONTCARE) and VISA (with VI_ATTR_DMA_ALLOW_EN = VI_TRUE) will use Interrupt mode even when a small number of bytes are expected.
•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 use Polling mode even sending a large number of bytes.
•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.
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