xgpib(7)                            CLIX                            xgpib(7)



  NAME

    xgpib - GPIB interface driver

  DESCRIPTION

    The xgpib driver is an asynchronous interface driver that provides bus
    control, device control, and data transfer functions for the IEEE 488-1978
    standard digital interface bus.  General Purpose Interface Bus (GPIB) is
    the common term for the IEEE 488 interface.

    The xgpib driver supports a maximum of NGPIB interface buses; NGPIB
    normally equals 1.  Using a channel approach, the driver associates the
    GPIB board in the lowest-numbered hardware slot with channel 0, the next
    GPIB board corresponds to channel 1, and so forth.  Generally, the channel
    number specified when using the GPIB library functions is 0, since only
    one GPIB board is typically in a system.  A process allocates a channel
    using the gpib_open() function.

    The xgpib driver accepts GPIB device addresses and performs the IEEE 488
    protocol based on the function.  For example, a process to clear a device
    on the bus simply sends the device's address to the driver using the
    gpib_clear() function.  The driver executes the protocol by sending the
    required bus commands.  This feature spares the user the task of
    formulating the protocols for every bus operation.

    The xgpib driver supports device-specific data transfers using hardware
    implemented Direct Memory Access (DMA) transfers.  The DMA capability
    provides expedient data throughput on the bus and allows the system CPU to
    perform other operations.

    The xgpib driver also provides a timeout capability with some functions
    allowing a process to implement error recovery procedures.  The timeout
    value specifies the number of 1/60-second intervals xgpib waits before
    aborting the function.  A timeout value of 0 always disables the timeout
    feature.

  CAUTIONS

    The xgpib driver requires primary device addresses and assumes the system
    is the only GPIB controller.

    The data transfer functions that use the DMA capability (gpib_read()
    andgpib_write()) have specific restrictions.  Data buffers must begin on
    longword (4-byte multiple) boundaries and read buffers must end on
    longword boundaries.

  RELATED INFORMATION

    Functions:  gpib_cancel(3), gpib_clear(3), gpib_close(3), gpib_cmd(3),
    gpib_local(3), gpib_lockout(3), gpib_open(3), gpib_ppconf(3),



  2/94 - Intergraph Corporation                                              1

  xgpib(7)                            CLIX                            xgpib(7)



    gpib_ppreq(3), gpib_ppuconf(3), gpib_read(3), gpib_remote(3),
    gpib_reset(3), gpib_service(3), gpib_spreq(3), gpib_trigger(3),
    gpib_write(3)



















































  2                                              Intergraph Corporation - 2/94