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Status Tutorial
This section provides a detailed description of the individual registers and register groups. The status diagram at the end
of this topic provides an graphical view of how the status registers and groups are interconnected.
Status Registers
Operation Status Group
Questionable Status Group
Standard Event Status Group
Status Byte Register
Error and Output Queues
Status Diagram
Status Registers
The Operation and Questionable status groups use four different type of registers to track qualify, flag, and enable
instrument events.
A Condition register continuously monitors the state of the instrument. The bits in the condition register are
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updated in real time and the bits are not latched or buffered
An PTR/NTR register qualifies the signal that passes to the event register. When a PTR bit is set, signals with pos-
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itive edge transition pass to the event register. When an NTR bit is set, signals with a negative edge transition pass
to the event register. When both bits are set, all signal pass. When neither bits are set, no signals pass.
An Event register latches the various events from the condition register. There is no buffering in this register;
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while an event bit is set, subsequent events corresponding to that bit are ignored. This is a read-only register
An Enable register defines which bits in the event register will be reported to the Status Byte register group. You
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can write to or read from an enable register.
To program individual bits in any register group, you must send a value that corresponds to the binary-weighted value
of all the bits that you wish to enable. For example, to enable bit 2 (decimal value = 4) and bit 4 (decimal value = 16),
the corresponding decimal value would be 20 (4 + 16).Similarly, any register queries return the binary-weighted value
of the bits that have been set. For example, with bit 3 (value 8) and bit 5 (value 32) being set, the query returns +40.
Operation Status Group
These registers record signals that occur during normal operation. The group consists of a Condition, PTR/NTR, Event,
and Enable register. The outputs of the Operation Status register group are logically-ORed into the OPERation sum-
mary bit (7) of the Status Byte register. Refer to
The following table describes the Operation Status register bit assignments.
Agilent N8900 Series Operating and Service Guide
Status Registers
for a description of each register.
Status Tutorial
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