Keithley KPCI-488 LPA, Руководство пользователя

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2-26 Return to Section Topics KPCI-488LPA-900-01 Rev. A / December 2008
Section 2: NI Command Compatible Functions Model KPCI-488LPA GPIB Controller Interface Card User’s Manual
ibrd
Description This command reads data from a device to the indicated buffer.
The GPIB is addressed by ibrd , which reads count data bytes (count is the counting
value in the counter); when ud is the device descriptor, the count data bytes are
placed in the user buffer. The operation ends when the count data bytes have been
read or when
END is read. If the count bytes reading does not finish before the
timeout period ends, the operation stops with an error. The actual number of
transferred bytes is returned in the global variable,
ibcntl .
When ud is the board descriptor , count data bytes are read by ibrd and placed in the
user buffer. The GPIB has already been addressed by the board-level ibrd ; the
operation ends when the count data bytes or END are read. If the count bytes reading
is not complete within the timeout period (or the board is not CIC, and CIC sends the
Device Clear message on the GPIB bus), the operation stops with an error. The
actual number of transferred bytes is returned in the global variable, ibcntl .
Support Level Board / device level
Syntax Microsoft C/C++ and Borland C++
int ibrd (int ud, void *buf, long cnt)
Visual Basic
ibrd (ByVal ud As Integer, buf As String,
ByVal cnt As Long) As Integer
- or -
call ibrd (ByVal ud As Integer, buf As String)
Parameters ud : device descriptor
buf : the buffer that stores the data that is read from the GPIB
cnt : the number of the bytes read from the GPIB
Return Value The value of the ibsta
Error Codes EABO, EADR, EBUS, ECIC, EDVR, ENEB, EOIP
ibrda
Description This command asynchronously reads data from a device to the designated buffer.
The GPIB is addressed by ibrda , which reads count data bytes (count is the counting
value in the counter); when ud is the device descriptor, the count data bytes are
placed in the user buffer. The operation ends when the count data bytes have been
read or when
END is read. If the count bytes reading does not finish before the
timeout period ends, the operation stops with an error. The actual number of
transferred bytes is returned in the global variable,
ibcntl .
Count data bytes are read by ibrda and placed in the user buffer when ud is the board
descriptor. The GPIB has already been addressed by the board-level ibrda ; the
operation ends when the count data bytes or END are read. If the count bytes reading
is not complete within the timeout period (or the board is not CIC, and CIC sends the
Device Clear message on the GPIB bus), the operation stops with an error. The
actual number of transferred bytes is returned in the global variable, ibcntl .
The design purpose of the asynchronous I/O commands ( ibcmda , ibrda , ibwrta ) is
that applications can perform other non-GPIB operations while the I/O is in progress.