86
Chapter 7
535-PROF User's Manual
Applications
C. ALARMS
The 535 controller has two extremely flexible and powerful software alarms. The
number of available outputs limits how alarms are linked to relays. A Global
Alarm feature allows all alarms to be assigned to the same relay.
The 535 indicates an alarm condition by:
• Lighting up the alarm icon(s)
• Displaying a custom message in the 3rd display
• Illuminating the
ACK
key (if the alarm is acknowledgeable)
Software Configuration
1. Access the
ALARM
menu.
2. Set values for the following parameters. All possible values are shown.
ALM.TYPE:1 and ALM. TYPE:2
Specifies the type of alarm to implement. Selection includes:
•
HIGH ALARM
High process variable alarm. Occurs when the process variable ex-
ceeds the alarm setpoint.
•
LOW ALARM
Low process variable alarm. Occurs when the process variable goes
below the alarm setpoint.
•
HIGH/LOW
Combination of high and low alarms. Occurs when the process vari-
able exceeds the individually set high or low setpoint.
•
BAND
Creates a band centered around the control setpoint, that is twice
the alarm setpoint. Alarm occurs when the process variable travels
outside of this band. The alarm is dependent on the control setpoint.
As the control setpoint changes, the band adjusts accordingly.
For example, if the control setpoint is 500 and the alarm setpoint is
25, then the band extends from 475 to 525.
•
DEVIATION
Similar to the band alarm but creates a band only on one side of the
control setpoint. Alarm occurs when the process variable deviates
from the control setpoint by an amount greater than the alarm setpoint.
This alarm is dependent on the control setpoint; as the control setpoint
changes, the alarm point changes.
For example, if the control setpoint is 500 and the alarm setpoint is
+50, then an alarm occurs when the process variable exceeds 550.
In order for an alarm to occur when the process variable drops below
450, select an alarm setpoint of –50.
•
MANUAL
Alarm occurs when the controller is put into manual mode of opera-
tion. This may be useful for security purposes or to alert the operator
that 535 is no longer under automatic control.
NOTE:
Specifying a variable other
than the setpoint (SP) to
HIGH
ALARM
and
LOW ALARM
allows for
greater flexibility in creating alarm
and control strategies.
