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Operation of the Status Byte
A service request is issued when bit 6 of the status
byte becomes "
". Bit 6 becomes "
1
other bits becomes "
1
" (or when the corresponding bit
in the service request enable register becomes "
For example, if an event occurs causing the logical
AND of any one bit in the standard event register and
the corresponding bit of the enable register to become
"
1
," bit 5 (ESB) is set to "
1
." In this case, if bit 5 of the
service request enable register is "
be set to "
1
", thus requesting service from the
controller.
It is also possible to check what type of event has
occurred by reading the contents of the status byte.
Reading from the Status Byte
The following two methods are provided for reading the
status byte.
• Inquiry using the *STB? query
Making an query using the
MSS. This causes the MSS to be read. After
completion of the read-out, none of the bits in the
status byte will be cleared.
• Serial poll
Execution of a serial poll changes bit 6 to RQS.
This causes RQS to be read. After completion of
the read-out, only RQS is cleared. Using a serial
poll, it is not possible to read MSS.
Clearing the Status Byte
No method is provided for forcibly clearing all the bits
in the status byte. Bits which are cleared are shown
below.
• When an query is made using the *STB? query
No bit is cleared.
• When a serial poll is performed
Only the RQS bit is cleared.
• When the *CLS command is received
When the
*CLS
command is received, the status
byte itself is not cleared, but the contents of the
standard event register (which affects the bits in the
status byte) are cleared. As a result, the
corresponding bits in the status byte are cleared,
except bit 4 (MAV), since the output queue cannot
be emptied by the
*CLS
command. However, the
output queue will also be cleared if the
command is received just after a program message
terminator.
IM 253710-11E
" when any of the
1
1
").
", bit 6 (MSS) will
1
*STB?
query sets bit 6 to
*CLS
5.2 Status Byte/5.3 Standard Event Register
5.3 Standard Event Register
Overview of the Standard Event Register
7
6
5
4
3
2
PON
URQ
CME EXE DDE QYERQCOPC
Bit 7 PON (Power ON)
Bit 7 PON (Power ON) Set to "
ON
Bit 6 URQ (User Request)
Not used (always "0")
Bit 5 CME (Command Error)
Set to "
1
" when the command syntax is incorrect.
Examples:
Incorrectly spelled command name;
received string data that have spelling
errors or that are not in the selection.
Bit 4 EXE (Execution Error)
Set to "
1
" when the command syntax is correct but the
command cannot be executed in the current state.
Examples:
Parameters are outside the setting
range: received a command that has a
parameter that is outside the range or a
command that deals with an option that
is not installed.
Bit 3 DDE (Device Dependent Error)
Set to "
1
" when execution of the command is not
possible due to an internal problem in the instrument
that is not a command error or an execution error.
Example:
The circuit breaker is reset.
Bit 2 QYE (Query Error)
Set to "
1
" if the output queue is empty or if the data is
missing even after a query has been sent.
Examples:
No response data; data is lost due to an
overflow in the output queue.
Bit 1 RQC (Request Control)
Not used (always "
0
")
Bit 0 OPC (Operation Complete)
Set to "
1
" when the operation designated by the
command has been completed. Refer to Chapter 4.
Bit Masking
To mask a bit in the standard event register so that it
does not cause bit 5 (ESB) of the status byte to
change, set the corresponding bit in the standard event
enable register to "
0
".
For example, to mask bit 2 (QYE) so that ESB will not
be set to "
1
", even if a query error occurs, set bit 2 of
the standard event enable register to "
done using the
*ESE
command. To inquire whether
each bit of the standard event enable register is "
"
0
", use the
*ESE?
. For details of the
refer to Chapter 4.
1
0
1
" when power is turned
*OPC
". This can be
0
" or
1
*ESE
command,
5-3
5
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