Page 26 - GuardII+ Series 4208 Platform EV User Manual

GuardII+ EV Card Operation

• Measurement status per input

• Measurement summary numbers per input
Refer to Section 8.2 for details of the EV Modbus register addresses.

4.8. GuardII+ Alerts

Alerts in a GuardII+ EV system are based on the Very-High alert thresholds configured in
IAM; when the measurement results are higher than one of the Very High thresholds for
multiple consecutive measurements, 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 alert thresholds must be set.
Refer to Section 6.3 for details on GuardII+ configuration.

The Alert is related to Level-Based Triggers described in Section 4.6.5; they use the same
thresholds. However, Alerts and Level-Based Triggers do not necessarily occur at the same
time; when a Very High Level Trigger occurs, the Alert will be asserted, but because of the
30-day Trigger interval an Alert can occur without a corresponding Trigger. For example:
• Suppose the monitor is configured for the first time, and the default Alert thresholds
are used.
• If the 2f Displacement Amplitude on input EV1 is higher than the Very High Alert
threshold for multiple consecutive measurements, then an Alert will occur almost
immediately; a Very High 2f Displacement Amplitude Trigger will also occur.
• If the Alert is reset but the Alert thresholds are not changed, then the Alert will turn off,
and then come back again very quickly. This Alert will not have a corresponding
Trigger saved because the EV1 Very High 2f Amplitude Displacement Trigger interval
has not expired yet.

4.8.1. Alert Relay
GuardII+ is equipped with a solid-state Alert Relay that can be programmed with one of
five behavior options using IAM:
• Disabled – the Alert Relay is not used.

• Normally Open, Latching – if there is no Alert condition, the relay contacts are open.
When an Alert is detected the relay will close and stay closed until reset.

• Normally Open, Momentary – if there is no Alert condition, the relay contacts are open.
When an Alert is detected the relay will close for 4 s and then automatically open again.

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