prog.book : chapter1.fm 72 Mon Feb 15 09:24:37 1999
Power Meter Remote Operation
Status Reporting
1-72 HP E4418B/E4419B Programming Guide
The General Status Register Model
The generalized status register model shown in Figure 1-10 is the building
block of the SCPI status system. This model consists of a condition
register, a transition filter, an event register and an enable register. A set
of these registers is called a status group.
Figure 1-10: Generalized Status Register Model
When a status group is implemented in an instrument, it always contains
all of the component registers. However, there is not always a
corresponding command to read or write to every register.
Condition Register
The condition register continuously monitors the hardware and firmware
status of the power meter. There is no latching or buffering for this
register, it is updated in real time. Condition registers are read-only.
Transition Filter
The transition filter specifies which types of bit state changes in the
condition registers will set corresponding bits in the event register.
Transition filter bits may be set for positive transitions (PTR), negative
transitions (NTR), or both. Transition filters are read-write. They are
unaffected by *CLS or queries. After STATus:PRESet the NTR register is
set to 0 and all bits of the PTR are set to 1.
Event Register
The event register latches transition events from the condition register as
specified by the transition filter. Bits in the event register are latched and
once set they remain set until cleared by a query or a *CLS. Once set, an
event bit is no longer affected by condition changes. It remains set until
the event register is cleared; either when you read the register or when
you send the *CLS (clear status) command. Event registers are read-only.
0
1
2
Bit 0
Bit 1
Bit 2
Bit 3
Condition
Register
Transition
Filter
Event
Register
Enable
Register
Logical OR
Summary
Bit
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