1269 User Manual
Using The Enhanced Monitoring System 4-10
presently being monitored (because a
“SENSE:VXI:IACK3:LIMIT” command was executed), then
clearing the counter for the BERR event will have no effect.
Generating an
Interrupt When an
Alarm Condition is
Detected
The previous paragraphs have described how to program
tolerance limits. When one of the attributes monitored by the
EMS exceeds its tolerance limits, an alarm condition exists.
The following paragraphs describe how to program the EMS to
generate an interrupt when it detects an alarm condition.
The EMS uses the SCPI-defined mechanism for generating
interrupts based on out-of-tolerance conditions. The EMS
implements a 3-level hierarchy of status registers to provide for
enabling and disabling of interrupts based upon the individual
VXI attributes monitored.
At the highest level, a separate condition, event, and enable
register is maintained for each of the following attributes:
Power Supply Voltages
Fan Speed
VXI Slot Temperatures
Elapsed Time
VXI Bus Error and IACK Events
Thus, there is a “Voltage Condition Register”, a “Voltage Event
Register”, a “Voltage Enable Register”, and so on.
The “Condition Register” holds the present status of each of the
individual items monitored. For example, the “Voltage
Condition Register” has a total of seven meaningful bits (see
Figure 4-1
). Each bit represents the present in-tolerance/out-
of-tolerance state of a single power supply voltage.
Bit 0 (the least significant bit) is set to 1 if the voltage for the
+5V power supply voltage is out of the programmable tolerance
limits. This bit is cleared to 0 if the +5V power supply voltage is
within the tolerance limits.
Similarly, bit 1 is set if the -5.2V power supply voltage is out of
tolerance, and cleared to 0 if it is in tolerance. The other bit
assignments for the
“Voltage Condition Register”
are shown
in
Figure 4-1
.
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