NAME
hpib_spoll() — conduct a serial poll on HP-IB bus (OBSOLETED AT 10.30)
SYNOPSIS
#include <dvio.h>
int hpib_spoll(int eid, int ba);
DESCRIPTION
hpib_spoll()
conducts a serial poll of the specified device.
eid
is an entity identifier of an open
HP-IB
raw bus device file obtained from an
open(),
dup(),
fcntl(),
or
creat()
call.
ba
is the bus address of the intended device.
hpib_spoll()
Polls a single device for its response byte.
The information stored in the response byte is device specific
with the exception of bit 6.
If bit 6 of the response byte is set,
the addressed device has asserted the
SRQ
line, and is requesting service
(note that the least significant bit of the response byte is bit 0).
Not all devices respond to the serial poll function.
Consult device documentation.
Specifying a device that does not support serial polling
may cause a timeout error or suspend your program indefinitely.
The interface cannot serial poll itself.
The interface must be the active controller.
RETURN VALUE
If
hpib_spoll()
is successful, the device response byte is returned
in the least significant byte of the return value.
Otherwise, -1 is returned, indicating an error.
ERRORS
hpib_spoll()
fails under the following circumstances, and sets
errno
(see
errno(2))
to the value in square brackets:
- [EBADF]
eid
does not refer to an open file.
- [ENOTTY]
eid
does not refer to an
HP-IB
raw bus device file.
- [EIO]
the interface is not the active controller.
- [ETIMEDOUT]
the device polled did not respond before timeout.
- [EINVAL]
ba
is the address of the polling interface itself.
- [EACCES]
The interface associated with this
eid
is locked by another process and
O_NDELAY
is set for this
eid
(see io_lock(3I)).
DEPENDENCIES
If the interface is not currently the active controller,
hpib_spoll()
sets
errno
to
[EACCES]
instead of to
[EIO].
AUTHOR
hpib_spoll()
was developed by HP.
