ibcmd() writes the command bytes
contained
in the array commands
to the bus. The number of bytes written from the array is specified by
num_bytes
. The ud
argument is a
board descriptor, and the
board must be controller-in-charge. Most of the
possible command bytes are declared as constants in the header files.
In particular, the constants GTL, SDC, PPConfig, GET, TCT, LLO, DCL, PPU, SPE,
SPD, UNL, UNT,and PPD are available. Additionally, the inline functions
MTA(), MLA(), MSA(), and PPE_byte() are available for producing
'my talk address', 'my listen address', 'my secondary address', and
'parallel poll enable' command bytes respectively.
It is generally not necessary to call ibcmd(). It is provided for advanced users who want direct, low-level access to the GPIB bus.