National Instruments NI-488.2 - Manual (Page 114)

Appendix C Error Codes and Solutions
NI-488.2 User Manual C-10 ni.com
Solutions
Ensure that the value being returned by your Callback function is a valid
ibnotify mask value.
Return a zero value from your Callback function to unregister the
asynchronous event notification mechanism. Then call
ibnotify to
re-enable notification.
EHDL (23)
EHDL results when an invalid handle is passed to a function call.
The following are some examples:
• A valid board handle is passed in as a handle parameter to a
device-level NI-488 function or a valid device handle is passed
in as a handle parameter to a board-level NI-488 function.
• An invalid board or device unit descriptor is passed as input to any
NI-488.2 function.
• A boardID outside the range of 0–99 is passed in to a traditional
NI-488 board-level function or NI-488.2 routine.
• ibconfig or ibask is called with a device unit descriptor and
a board-only configuration option, or with a board unit descriptor
and a device-only configuration option.
Solutions
Do not use a device descriptor in a board function or vice-versa.
Make sure that the board index passed to the NI-488.2 call is valid.
EWIP (26)
EWIP indicates that an ibwait call is already in progress on the specified
unit descriptor. This error occurs when one thread within a process calls
ibwait on a given descriptor when another thread within the same process
is already performing an ibwait using that same descriptor.
Solutions
Make sure that for any given unit descriptor only one thread calls ibwait
at a time using that descriptor.