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GPIB IEEE Std. 488.2 Error Handling – Query Error Register
The IEEE 488.2
If the instrument is addressed to talk and the response formatter is inactive and the input queue is
empty then the
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
send a response message and a
or the input queue contains more than one END message then the instrument has been
INTERRUPTED
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>
further information.
The IEEE 488.2
a response message and the input queue becomes full then the instrument enters the
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
MESSAGE UNIT>
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
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
The instrument must also be configured so that the value of
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 =
bit 6 =
bit 5 =
bit 4 =
bit 3 =
bit 2 =
bit 1 =
bit 0 =
Example.
The parallel poll response from the instrument will then be 00H if RQS is 0 and 01H if RQS
is 1.
During parallel poll response the DIO interface lines are resistively terminated (passive
termination). This allows multiple devices to share the same response bit position in either wired-
AND or wired-OR configuration, see IEEE 488.1 for more information.
error (addressed to talk with nothing to say) is handled as follows.
UNTERMINATED
error is generated. This will cause the Query Error bit to be set in
UNTERMINATED
error is handled as follows. If the response formatter is waiting to
INTERRUPTED
<PROGRAM MESSAGE TERMINATOR>
and an error is generated. This will cause the Query Error bit to be set in the
error is handled as follows. If the response formatter is waiting to send
DEADLOCK
from the input queue. See the Status Reporting section for further information.
X
don't care
1
1
Parallel poll enable
0
Sense
sense of the response bit; 0 = low, 1 = high
?
?
bit position of the response
?
To return the RQS bit (bit 6 of the Status Byte Register) as a 1 when true and a 0
when false in bit position 1 in response to a parallel poll operation send the
following commands
*PRE 64
<pmt>,
from the input queue. See the Status Reporting section for
is 0 otherwise the value of
ist
then PPC followed by 69H (PPE)
has been read by the parser
is 1.
ist
can be returned to the controller
ist
DEADLOCK
<PROGRAM
local
ist
31
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