National Instruments GPIB-PC - Manual (Page 46)

Section Three GPIB-PC Functions — Introduction
©National Instruments Corp. 3-3 GPIB-PC User Manual
IBFIND (bdname,bd)
IBFIND returns a unit descriptor associated with the name of the
device. When the software is installed, a description of each device is
placed in an internal reference table accessible by the handler. This
description includes the GPIB address, end-of-string (EOS) modes,
timeout selection, and a name for the device.
Group II
Group II functions offer additional high-level device services often
needed in common instrument control applications. Group II functions
are as follows:
• IBRSP ,
• IBCLR ,
• IBTRG , and
• IBLOC .
IBRSP (bd,spr)
IBRSP serially polls a device and returns its status response. The
response consists of a single byte in which the hex 40 bit is set if the
device is requesting service and asserting Service Request (SRQ).
Here are examples of a Tektronix 4041 BASIC SRQ handler call and
the corresponding
IBRSP call. In this case, the device being polled is
the plotter and is at GPIB address 7:
POLL STATUS, ADDRESS; 7
CALL IBRSP (PLTR%,STATUS%)
In both cases, the plotter's status response is stored in the variable
STATUS .
Unless disabled during software configuration, any device function call
will automatically conduct serial polls if SRQ is asserted on GPIB. This
automatic serial polling is discussed in Section Four.