Troubleshooting Guidelines | 2 |
The default behavior of the 82350 driver is to use Polling mode for transfers of 256 bytes or less and to use Interrupt mode for larger transfers. You can modify this default behavior by doing the following:
SICL: The SICL ihint(id, hint) function can be called to modify the read/write behavior for on a SICL session. The hint values allowed are:
1I_HINT_DONTCARE (default value) Use Interrupt mode for transfer requests larger than 256 bytes, otherwise, use Polling mode.
2I_HINT_USEPOLL Use the Polling mode.
3I_HINT_IO Use the Interrupt mode.
VISA: The VISA viSetAttribute(vi, VI_ATTR_ DMA_ALLOW_EN, attrValue) function can be called to modify the read/write behavior for a VISA session. The VI_ATTR_DMA_ALLOW_EN values allowed are:
•VI_TRUE (default value) Use Interrupt mode for transfer requests larger than 256 bytes, otherwise, use Polling mode.
•VI_FALSE Use the Polling mode.
Some additional factors to consider are:
•The settings discussed above are per session. This means you can open multiple sessions to a device and set different transfer modes for different sessions. The actual mode used will then depend on which session you are using for the read/write calls.
•In both SICL (with hint =
I_HINT_DONTCARE) and VISA (with
VI_ATTR_DMA_ALLOW_EN = VI_TRUE), the size of the read request (as specified by bufsize in a SICL iread() or count
in a VISA viRead() function call) will determine the mode used even if the number of bytes actually read is less.
82350B Installation and Configuration Guide | 43 |