National Instruments NI-488.2 ユーザーズマニュアル
Chapter 4
Developing Your NI-488.2 Application
© National Instruments Corporation
4-5
Status Word (ibsta)
All NI-488.2 calls update a global status word,
ibsta
, which contains
information about the state of the GPIB and the GPIB hardware. The value
stored in
stored in
ibsta
is the return value of all the traditional NI-488.2 calls,
except
ibfind
and
ibdev
. 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
If you check for possible errors after each call using the
ibsta
ERR bit,
debugging your application is much easier.
ibsta
is a 16-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. Each bit in
is not in effect. 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).
multi-device NI-488.2 calls (brd), or all (dev, brd).
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,
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,
.
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
service
CMPL
8
100
dev, brd
I/O completed
LOK
7
80
brd
Lockout State
REM
6
40
brd
Remote State
CIC
5
20
brd
Controller-In-Charge
ATN
4
10
brd
Attention is asserted
TACS
3
8
brd
Talker
LACS
2
4
brd
Listener