Allen-Bradley 1444-AOFX00-04RB, Руководство пользователя, Страница: 228 / 550

228 Rockwell Automation Publication 1444-UM001D-EN-P - June 2018
Chapter 8 Configure Alarms
The module provides two methods of gating: speed and I/O (Logic) gate
control.
Speed gating lets you select either of the two speed inputs, either the direct or
factored speed value, a high and/or low speed limit, and the customary
conditional (<, ≤, ≥, >). The gate is TRUE and the voted alarm that is applied
when the measured speed satisfies the condition (evaluates to TRUE).
For I/O (Logic) gate control, the control signal can be provided either from the
controller, via its control output tag, or from either of the discrete inputs when
properly assigned. (See
Hardware Configuration Page on page 111 .)
For controller-based gate management, 2 bits are provided in the controller
output control tag (bits 5 and 6). Either control (0/1) can be specified for each
voted alarm. When the control bit is set (1), then the gate is TRUE and the
voted alarm is evaluated.
Use of either of the discrete inputs also controls gating. The assigned discrete
input must be configured on the Hardware Configuration page, and must also
be selected (0/1) in the specific voted alarm definition.
Relay Control
When a relay is assigned a voted alarm as its input, it inherits the voted alarm
latching and fail-safe definitions.
Latching
Latching applies to both the (logical) voted alarm and to any associated
physical relay. When an alarm is latched, it cannot be reset until the condition
has cleared (is no longer in the alarm state). Once the condition has cleared, the
latch is reset using either the
Output Assembly Alarm Reset bit or a physical
reset switch that is wired to the one of the discrete inputs (see Hardware
Configuration Page on page 111 ).
There are four methods available to reset a voted alarm, and all relays that
reference it:
• Controller Output: 2 bits are included in the control tag of the
controller output.
• Discrete Inputs: Either of the two discrete inputs can be assigned to reset
alarms. (See Hardware Configuration Page on page 111 .)
• Either of two alarm reset service requests can be sent to the module.
• The AOP status page, which executes the service request.
Each voted alarm includes a control selection that defines which of the two
inputs (of any of the previous types) is used to reset the alarm. In this way, it is
possible to define a more discrete control over which voted alarms are reset on
command.