National Instruments GPIB-PC - Manual (Page 69)

GPIB-PC Functions — Overview Section Four
GPIB-PC User Manual 4-8 ©National Instruments Corp.
address to the device in the handler.
For a board write, an IBCMD call is generally necessary to
address devices before an IBWRT . Be sure that the proper
listen address is in the IBCMD argument string and that no
Unlisten (hex 3F) command follows it.
ENOL may occur in situations in which the GPIB-PC is not
the CIC and the Controller asserts ATN before the write
call in progress has ended. The remedy is either to reduce
the write byte count to that which is expected by the
Controller, or to resolve the situation on the Controller's
end.
EADR (3) EADR occurs when the GPIB-PC is CIC and is not
addressing itself before read and write calls are made. This
error is extremely unlikely to occur on a device call. For a
board call the remedy is to be sure to send the appropriate
Talk or Listen address using
IBCMD before attempting the
IBWRT or IBRD .
EADR is also returned by the function IBGTS when the
shadow-handshake feature is requested and the GPIB ATN
line is already unasserted. In this case, the shadow
handshake is not possible and the error is returned to notify
you of that fact.
IBGTS should almost never be called
except immediately after an IBCMD call. ( IBCMD causes
ATN to be asserted.)
EARG (4) EARG results when an invalid argument is passed to a
function call. The following are some examples:
IBTMO called with a value not in the range 0-17.
IBEOS called with meaningless bits set in the high byte of
the second parameter.
IBPAD or IBSAD called with illegal addresses.
IBPPC called with illegal parallel poll configurations.
A board-only call made with a valid device descriptor, or a
device-only call made with a valid board descriptor.
(NOTE: EDVR is returned if the descriptor is invalid.)
ESAC (5) ESAC results when IBSIC or IBSRE is called when the