Page 125 - GuardII+ Series 4208 Platform PD User Manual

Appendix

NOTE:
If the measurement results are consistently showing that one or more
Quality Flags are set, consult Iris Power LP Technical Support for
assistance with interpreting measurement results.

8.3.2. Qm Calculation Exceptions
Qm represents the peak PD activity, and is calculated from the data collected; however,
there are times when the Qm cannot be calculated. In these cases, the Qm values will be set
to a pre-determined number and the Invalid Qm Measurement Status Bit will be set.

NOTE:
A failure to calculate Qm does not necessarily mean a problem with the
GuardII+; it is usually an indicator that it is time to make some configuration
changes.
• If the measurement did not complete, the Qm will report a value of ‘0’.

• If the Qm cannot be calculated because the pulse counts are too high, the Qm will
report a value of maximum scale; for example, on the 20-340mV sensitivity the Qm
would be ‘340’, and on the 100-1700mV sensitivity the Qm would be ‘1700’. Most of
the time when this occurs Over Range status bit will also be set.

8.3.3. NQN Calculation Exceptions
Like Qm, there are also cases for which the NQN cannot be calculated. The Modbus NQN
outputs will follow these rules:
• If the measurement did not complete, the NQN will report a value of ‘0’.

• If the NQN cannot be accurately determined because the pulse counts are too high,
the NQN value will still be calculated; the Over Range status bit will also be set.

8.4. Modbus Slave Timing

NOTE:
As described in Section 4.2, GuardII+ updates the PD Modbus data
registers after every measurement cycle. Each measurement cycle takes
up to 65 minutes to complete; so, while the monitor can respond to
Modbus requests very quickly, the PD data simply will not change that
often. Polling the monitor every few seconds is just wasting network
bandwidth.
Each monitoring technology in the GuardII+ Series 4208 Platform has its
own measurement cycle; so If the monitor has other monitoring
technologies installed, those other technologies may provide Modbus
updates more rapidly.

To achieve the best performance when polling GuardII+’s Modbus data registers, the
following configurations of the polling system should be used:

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