Errors While Sending Commands - HP 9000 Series 300 Tutorials Manual

Errors While Sending Commands
Normally, hpib_send_cmnd returns a 0 if successful. It returns a -1 if anyone
of the following error conditions exist:
• Computer interface is not Active Controller.
• eid entity identifier does not refer to an HP-IB raw interface file.
• eid entity identifier does not refer to an open file.
• A timeout occurs.
• The interface associated with this eid is locked by another process and
D_NDELAY
is set for this eid.
• The command length specified by number is invalid.
To determine which of these conditions caused the error, check the value of
errno, an external integer variable used by HP-UX system calls. Error-checking
routines are discussed at length in Chapter 2.
The following table lists errno values corresponding to the conditions above
when detected by hpib_send_cmnd:
errno Value
EBADF
ENOTTY
EIO
Error Condition
eid
did not refer to an open file
eid did not refer to a raw interface file
The interface was not the Active Controller (EACCES on Series 800)
ETIMEDOUT A timeout occurred (EIO on Series 300)
EACCES
EINVAL
The interface associated with this
eid
was locked by another process
and
D_NDELAY
was set for this eid
number was invalid, either less than or equal to 0 or greater than
MAX_HPIB_CDMMANDS
as defined in
dvio.h
3-16 Controlling the HP-IB Interface