Alarms Set Up Group - Honeywell UDC3500 Product Manual

Configuration

3.21 Alarms Set Up Group

Introduction
The UDC3500 has four alarms and eight alarm setpoints. Each alarm has its own
hysteresis configuration.
An alarm is an indication that an event that you have configured (for example—Process
Variable) has exceeded one or more alarm limits. There are up to four alarms available.
Each alarm has two setpoints. You can configure each of these two setpoints to alarm on
various controller parameters.
There are two alarm output selections for each alarm setpoint, High and Low. These
allow you to choose whether the alarm activates when the measured value is above
(High) or below (Low) the alarm setpoint. You can also configure the two setpoints to
alarm on the same event and to alarm for both high and low conditions.
An adjustable Hysteresis of 0 % to 100 % is provided for each alarm.
Alarms may be conveniently broken up into four types:
1. Analog – These are alarms, which monitor selections that use analog values,
such as Process Variable, Set Points or analog inputs. These alarms require a
hysteresis value.
2. Digital – These are alarms which monitor status that are either ON or OFF,
such as Mode (e.g., Manual), Digital Input status. These alarms do not use a
hysteresis value.
3. Events – The alarms are only used with Set Point Programming and may be
configured to operate at the beginning or end of a particular segment.
4. Loop Break – Loop Break is a special kind of alarm, which monitors the
control loop. Although this is a digital alarm (i.e., the alarm is either broken or
it is not), it requires that an analog value to be configured in order to operate
properly.
See Table 2-3 in the Installation section for Alarm relay contact information.
ATTENTION
If the controller is configured to use the same relay for more than one function, then the
following priority is used to determine how the relay functions: Control Outputs take
precedence over Alarms, which in turn take precedence over Time/Events, which in turn
take precedence over Logic Gate Outputs. For example, if you select the Loop 2 Output
Algorithm as Time Simplex (which uses Relay 3), enable Alarm 3 (which also uses
Relay 3) and configure a Logic Gate to use Relay 3, then the instrument will use Relay
#3 to perform the Time Simplex output and ignore the Alarm and Logic Gate functions.
The prompts for the Alarm Outputs appear whether or not the alarm relays are
physically present or used for some other function. This allows the Alarm status to be
shown on the display and/or sent via communications to a host computer.
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