National Instruments GPIB-PC - Manual (Page 122)

Section Four A BASICA/QuickBASIC GPIB-PC Function Calls
©National Instruments Corp. 4A-47 GPIB-PC User Manual
BASICA/QuickBASIC BASICA/QuickBASIC
IBRD IBRD
Purpose: Read data to string
Format: CALL IBRD (BD%,RD$)
Remarks: BD% specifies a device or an interface board. RD$
identifies the storage buffer for data bytes that are read
from the GPIB.
The IBRD function reads from 1 to 255 bytes of data from a
GPIB device. In QuickBASIC the IBRD function reads
from 1 to 32K bytes of data from a GPIB device.
Device IBRD Function:
When BD% specifies a device, the following board steps are performed
automatically to read from the device:
1. The IBCMD function is called to address the device to talk and
the access board to listen.
2. The board IBRD function is called to read the data from the
device, as explained in the following discussion.
3. The IBCMD function is called to unaddress the access board
and unaddress all devices using the Untalk and Unlisten
commands.
Other command bytes may be sent as necessary.
When the device IBRD function returns, IBSTA% holds the latest
device status; IBCNT% is the actual number of data bytes read from the
device; and IBERR% is the first error detected if the ERR bit in IBSTA%
is set.
Board IBRD Function:
When BD% specifies an interface board, the IBRD function attempts to
read from a GPIB device that is assumed to already be properly
initialized and addressed.
If the access board is CIC, the IBCMD function must be called prior to
IBRD to address a device to talk and the board to listen. Otherwise, the
device on the GPIB that is the CIC must perform the addressing.