20
GPIB Subsets
This instrument contains the following IEEE 488.1 subsets:
Source Handshake
SH1
Acceptor Handshake
AH1
Talker
T6
Listener
L4
Service Request
SR1
Remote Local
RL2
Parallel Poll
PP1
Device Clear
DC1
Device Trigger
DT0
Controller
C0
Electrical Interface
E2
GPIB IEEE Std. 488.2 Error Handling – Query Error Register
The IEEE 488.2
UNTERMINATED
error (addressed to talk with nothing to say) is handled as follows.
If the instrument is addressed to talk and the response formatter is inactive and the input queue is
empty then the
UNTERMINATED
error is generated. This will cause the Query Error bit to be set in
the Standard Event Status Register, a value of 3 to be placed in the Query Error Register and the
parser to be reset. See the Status Reporting section for further information.
The IEEE 488.2
INTERRUPTED
error is handled as follows. If the response formatter is waiting to
send a response message and a
<PROGRAM MESSAGE TERMINATOR>
has been read by the parser
or the input queue contains more than one END message then the instrument has been
INTERRUPTED
and an error is generated. This will cause the Query Error bit to be set in the
Standard Event Status Register, a value of 1 to be placed in the Query Error Register and the
response formatter to be reset thus clearing the output queue. The parser will then start parsing
the next
<PROGRAM MESSAGE UNIT>
from the input queue. See the Status Reporting section for
further information.
The IEEE 488.2
DEADLOCK
error is handled as follows. If the response formatter is waiting to send
a response message and the input queue becomes full then the instrument enters the
DEADLOCK
state and an error is generated. This will cause the Query Error bit to be set in the Standard Event
Status Register, a value of 2 to be placed in the Query Error Register and the response formatter
to be reset thus clearing the output queue. The parser will then start parsing the next
<PROGRAM
MESSAGE UNIT>
from the input queue. See the Status Reporting section for further information.
GPIB Parallel Poll
Complete parallel poll capabilities are offered on this instrument. The Parallel Poll Enable Register
is set to specify which bits in the Status Byte Register are to be used to form the
ist
local message
The Parallel Poll Enable Register is set by the *PRE <
NRF
> command and read by the *PRE?
command. The value in the Parallel Poll Enable Register is ANDed with the Status Byte Register; if
the result is zero then the value of
ist
is 0 otherwise the value of
ist
is 1.
The instrument must also be configured so that the value of
ist
can be returned to the controller
during a parallel poll operation. The instrument is configured by the controller sending a Parallel
Poll Configure command (PPC) followed by a Parallel Poll Enable command (PPE). The bits in the
PPE command are shown below:
bit 7 =
X
don't care
bit 6 =
1
bit 5 =
1
Parallel poll enable
bit 4 =
0
