1261B User Manual
Using The Enhanced Monitoring System 4-6
Racal Instruments
Ó
1995
Monitoring The VXI
Subsystem
The 1261B EMS has the ability to monitor the VXI power
supplies’ voltage and current, VXI slot temperatures, fan speeds,
and select VXI signals. When one of these is outside the user-
specified limits, an interrupt can be generated. This allows the
system controller (computer) to effectively monitor the VXI
subsystem without having to continually poll the 1261B EMS.
Each attribute is checked once per second, at a minimum, by the
EMS. If the attribute value is outside the programmed limits, an
“alarm” condition is assumed to exist. If the EMS has been told
to generate an interrupt when the alarm condition exists, an
interrupt will be sent to the system controller (by asserting one of
the VXI interrupt lines IRQ1 to IRQ7).
When the system controller detects the interrupt, it can read
status registers on the EMS to determine which attribute is at
fault. It can then query the EMS to determine the present value
of the attribute. It can also query the EMS to determine the time
and date of the alarm condition.
Programming the EMS to perform this monitoring is done as a
two-step process:
1)
Program the tolerance limits for the attribute
2)
Program the status registers to generate an interrupt
when the attribute is outside its tolerance limits.
Programming The
Tolerance Limits
The various SENSE commands are used to set the
programmable tolerance limits for the various attributes
monitored by the 1261B EMS. The following paragraphs
describe how to set each attribute’s tolerance limit or limits.
Refer to
Table 5-2
for a description of the range of values
accepted for each command.
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