Page 32 - GuardII+ Series 4208 Platform PD User Manual

PD Card Operation

4.7. Modbus Outputs

PD Measurement data is hosted inside the monitor for an external Modbus master to read.
To access the data registers, connect to the GuardII+ using Ethernet and query the monitor
using the standard Modbus over TCP/IP protocol. This data is updated during every
measurement cycle. Modbus data outputs include (for each combination of input and range):
• Measurement time

• Measurement status
• Summary numbers
• 2D data

• Modbus data outputs do not include raw data.
• Alert status

Refer to Section 8.2 for the list of Modbus PD register addresses.

4.8. GuardII+ Alerts

Alerts in a GuardII+ PD system are based on the Very High Qm threshold configured in
IAM; when any measurement produces Qm results higher than the Very High threshold for 4
consecutive measurement cycles, the Alert is asserted.
NOTE:
There are two configurations that need to be completed using IAM for the
Alert feature to function fully:

• First, there is a general Alert Relay behavior that must be set to a
selection other than ‘Disabled’; if the Alert Relay behavior is not
configured, then the Alert Relay will not function, although Archived
measurements and Modbus data will still report an Alert when it
occurs.

• Second, the Very High threshold must be set.

Refer to Section 6.3 for details on GuardII+ configuration.

NOTE:
One recommended use of the User Defined Trigger is to capture additional
data once an Alert has occurred; the Alert is an indicator that PD levels
have reached a point to cause concern, so some more frequent data
collection is a good idea.

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