National Instruments GPIB-PC - Manual (Page 45)

GPIB-PC Functions — Introduction Section Three
GPIB-PC User Manual 3-2 ©National Instruments Corp.
Group I
Group I functions may be the only functions you need for many of your
instrument control applications. Group I functions are as follows:
• IBRD ,
• IBWRT , and
• IBFIND .
They are suitable for your applications under the following conditions:
• Communication is between the Controller (computer) and one
device at a time. Messages are not broadcast to several
devices at once, and devices do not talk to each other directly.
• Devices do not require special services or operations, such as
polling or triggering, to send or receive data.
IBRD and IBWRT are high-level input/output (I/O) functions. IBFIND
is a start-up function that opens the device.
IBRD (bd,buf,cnt)
IBRD reads a specified number of bytes from a device and stores them
in memory. The device is automatically addressed before reading and
unaddressed afterward. If not done previously, the GPIB is initialized on
entering the function and the device is placed in remote programming
mode.
When programming in BASIC, IBRD performs string transfers. IBRDI
is available for binary transfers to an integer array.
IBWRT (bd,buf,cnt)
IBWRT writes a specified number of bytes from the memory buffer to a
device. The device is automatically addressed before writing and
unaddressed afterward. If not done previously, the GPIB is initialized on
entering the function, and the device is placed in remote programming
mode.
When programming in BASIC, IBWRT performs string transfers.
IBWRTI is available for binary transfers from an integer array.