ibwrt() is used to write data bytes to a device or board. The argument
ud
can be either a device or board descriptor.
num_bytes
specifies how many bytes
are written from the user-supplied array data
.
EOI may be asserted with the last byte sent or when the end-of-string
character is sent (see ibeos() and ibeot()). The write operation
may be interrupted by a timeout (see ibtmo()), the board receiving a device clear command, or
receiving an interface clear.
If ud
is a device descriptor, then the library
automatically handles addressing the device as listener and the interface
board as talker, before sending the data bytes onto the bus.
If ud
is a board descriptor, the board simply writes the data onto the bus. The
controller-in-charge must address the board as talker.
After the ibwrt() call, ibcnt and ibcntl are set to the number of bytes written.