HP 9000 Series 300 Tutorials Manual page 172

hpib_card_ppolI_resp
Calling hpib_card_ppoll_resp on an auto-addressed file does not configure
the HP-IB interface card; rather, it configures the device associated with the
file with the appropriate addressing and Parallel Poll configuration commands.
hpib_io
For those iodetail structures that send commands (by setting the mode flag
to HPIBWRITE or HPIBATN), hpib_io prefixes the command buffer buf
with the appropriate device addressing (see hpib_send_cmd, below). For data
transfers (with mode set to HPIBREAD or HPIBWRITE) using auto-addressed
files, the addressing is also done for you.
hpib_ren_ctl
Setting REN (by setting the flag parameter to a non-zero value) on an
auto-addressed file addresses the associated device before asserting REN.
Clearing REN (by setting flag to a zero) addresses the device and sends it a Go
To Local command, in lieu of clearing REN.
hpib_send_cmd
Sending HP-IB commands to an auto-addressed file via hpib_send_cmd does
the appropriate device addressing for you. The command buffer you pass down
to the device is preceded by the commands necessary to remove any previous
listeners on the bus, address the Active Controller to talk, and configure the
file's associated device to listen.
Performing a serial poll on an auto-addressed file polls the associated device;
any bus address passed via the ba argument is ignored.
8-10 Series 800 Dependencies