Allen-Bradley 1444-TSCX02-02RB User Manual page 227

Voted alarms enable definition of several control attributes, and the condition
and inputs for the logical assessment are also defined. These include managing
setpoint multiplication, gating controls, and relay controls.
Setpoint Multiplication
SPM enables application of the limit multiplier to any measurement alarms
that are linked to the voted alarm, where the measurement alarm is applying
only static limits. SPM control includes two items: the input to use and any
hold period required.
SPM Control Input
The SPM function can be controlled from either of two inputs. These inputs
can be either the SPM bits included in the controller output assembly (bits 1
and 2), or either of the physical discrete inputs to the module (Pt0, Pt1) that
can be assigned to this function (See
page 111). The selection lets either controller output tag SPM 0/Pt0 or
controller output tag SPM 1/Pt1 be used.
A second attribute, hold time, is also provided for SPM control. This value is
used to define how long the SPM function remains active AFTER the SPM
control has changed state. The timer starts (or restarts) each time the output
assembly control bit, SetPointMultiplier0En/ SetPointMultiplier0En, is set or
cleared. Or, if you use the digital inputs, the timer starts (or restarts) each time
Pt(0) / Pt(1) is closed or opened. This behavior is intended to force continued
positive assertion of the function, which precludes users from inadvertently
leaving the SPM function enabled.
As an alternative to the timer, the module provides speed-based multiplication.
See Adaptive Multipliers on page
Gating
Gating is used to specify when a voted alarm is applied. While the gate
condition is TRUE, the voted alarm is evaluated. If the gate condition is
FALSE, the voted alarm is not evaluated.
Any defined gate condition must be satisfied as a prerequisite to the voted
alarm. If the voted alarm is TRUE when the gate condition becomes FALSE, then
the voted alarm transitions to FALSE, unless it is latched. See
page 228. And, unless latched, any relays that are assigned to the voted alarm
are also transitioned.
Rockwell Automation Publication 1444-UM001D-EN-P - June 2018
Configure Alarms
Hardware Configuration Page on
220.
Chapter 8
Latching on
227