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The Status Model
HP 8163A Lightwave Multimeter, HP 8164A Lightwave Measurement System,
& HP 8166A Lightwave Multichannel System User's Guide, E1299
The Status Model
Status Registers
Each node of the status circuitry has three registers:
• A condition register (CONDition), which contains the current status. This
register is updated continuously. It is not changed by having its contents read.
• The event register (EVENt), which contains details of any positive transitions
in the corresponding condition register, that is, when a bit changes from 0 → 1.
The contents of this register are cleared when it is read. The contents of any
higher-level registers are affected with regard to the appropriate bit.
• The enable register (ENABle), which enables changes in the event register to
affect the next stage of registers.
N O T E
The event register is the only kind of register that can affect the next stage of
registers.
The structures of the Operational and Questionable Status Systems are similar.
Figure 4 describe how the Questionable Status Bit (QSB) and the Operational
Status Bit (OSB) of the Status Byte Register are determined.
1 1 1 1 1
Figure 3
The Registers and Filters for a Node
Introduction to Programming
Enable Registers
To the
OR
Condition Register
of the Next Node
Event Registers
A positive transition in the condition
register, when a bit changes from 0 → 1,
causes the corresponding bit of the
corresponding event register
to change from 0 → 1.
Condition Registers
25
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