National Instruments NI-488.2 - Manual (Page 44)

Chapter 4 Developing Your NI-488.2 Application
© National Instruments Corporation 4-7 NI-488.2 User Manual
if the sizes of ibcnt and ibcntl are the same, ibcnt and ibcntl are
equal. For cross-platform compatibility, all applications should use
ibcntl .
For applications accessing the newer NI4882 API, use the global function
calls rather than the global variables. The global functions replace the
global variables with the newer NI4882 API.
Note If your application is a multithreaded application, refer to the Writing Multithreaded
NI-488.2 Applications section in Chapter 8, NI-488.2 Programming Techniques .
Status Word (Ibsta)
All calls update a global status function, Ibsta , which contains
information about the state of the GPIB and your GPIB hardware. You can
examine various status bits in
Ibsta and use that information to make
decisions about continued processing. If you check for possible errors after
each call using the
Ibsta ERR bit, debugging your application is much
easier. When using the GPIB32 API, ibsta is the global variable.
Each bit in Ibsta can be set for device-level traditional NI-488.2 calls
(dev), board-level traditional NI-488.2 calls and multi-device NI-488.2
calls (brd), or all (dev, brd).
Ibsta is a 32-bit value. A bit value of one (1)
indicates that a certain condition is in effect. A bit value of zero (0)
indicates that the condition is not in effect.
Table 4-1 shows the condition that each bit position represents, the bit
mnemonics, and the type of calls for which the bit can be set. For a detailed
explanation of each status condition, refer to Appendix B,
Status Word
Conditions .
Table 4-1. Status Word Layout
Mnemonic
Bit
Pos
Hex
Value Type Description
ERR 15 8000 dev, brd NI-488.2 error
TIMO 14 4000 dev, brd Time limit exceeded
END 13 2000 dev, brd END or EOS detected
SRQI 12 1000 brd SRQ interrupt received
RQS 11 800 dev Device requesting
service