IBWRTA

NI-488.2

IBWRTA

Board-Level/Device-Level


Purpose

Write data asynchronously to a device from a user buffer.

Format

C

unsigned long ibwrta (int ud, const void *wrtbuf, size_t count)

Visual Basic

CALL ibwrta (ud%, wrtbuf$)

or

status% = ilwrta (ud%, wrtbuf$, count&)

Interactive Control (Usage Notes)

ibwrta wrtbuf

Input

ud Board or device descriptor
wrtbuf Address of the buffer containing the bytes to write
count Number of bytes to be written

Output

Function Return The value of Ibsta

Description

Device-Level

If ud is a device descriptor, ibwrta addresses the GPIB properly and writes count bytes from wrtbuf to a GPIB device. The operation terminates normally when count bytes have been sent. The actual number of bytes transferred is returned in the global function Ibcnt.

Board-Level

If ud is a board descriptor, ibwrta begins an asynchronous write of count bytes of data from wrtbuf to a GPIB device. A board-level ibwrta assumes that the GPIB is already properly addressed. The operation terminates normally when count bytes have been sent. The operation terminates with an error if the board is not the CIC, and the CIC sends a Device Clear on the GPIB. The actual number of bytes transferred is returned in the global function Ibcnt.

Board- and Device-Level

The asynchronous I/O calls (ibcmda, ibrda, ibwrta) are designed so that applications can perform other non-GPIB operations with the I/O in progress. Once the asynchronous I/O begins, further NI-488.2 calls are strictly limited. Any calls that would interfere with the I/O in progress are not allowed; the driver returns EOIP in this case.

Once the I/O is complete, the application must resynchronize with the NI-488.2 driver. Resynchronization is accomplished by using one of the following calls:

ibwait If the returned Ibsta contains CMPL, the driver and application are resynchronized.
ibnotify If the Ibsta value passed to the ibnotify callback contains CMPL, the driver and application are resynchronized.
ibstop The I/O is canceled; the driver and application are resynchronized.
ibonl The I/O is canceled and the interface is reset; the driver and application are resynchronized.

Possible Errors

EABO Board-level: A Device Clear message was received from the CIC.
EADR Board-level: The GPIB is not correctly addressed; use ibcmd to address the GPIB.
Device-level: A conflict exists between the device GPIB address and the GPIB address of the device access board. Use the IbcPAD and IbcSAD options in ibconfig.
EARG Either the buffer or the count is invalid.
EBUS Device-level: No devices are connected to the GPIB.
ECIC Device-level: The access board is not CIC. See Device-Level Calls and Bus Management.
EDVR The NI-488.2 driver is either configured incorrectly or is not properly installed.
EHDL ud is invalid or out of range.
ELCK The requested operation could not be performed because of an existing lock by another process.
ENEB The interface is not installed or is not properly configured.
ENOL No Listeners were detected on the bus.
EOIP Asynchronous I/O is in progress.