West Control Solutions Pro-EC44 - Manual (Page 214)

Pro-EC44 2-Loop Graphical Profile Controller & Recorder
Pro-EC44 Product Manual - 59540-1 October 2013 Page 207
Alarm Types
There are three basic alarm types, Process Alarms, Control Deviation Alarms and Event
Based Alarms; plus some special condition alarms.
Process Alarms are based on the absolute value of the Process Variable. If the PV rises
above a high alarm value, or falls below a low alarm value, the alarm will become active.
Control Deviation Alarms are based on the value of the Control Deviation error. If the PV is
more than the high deviation alarm value above setpoint, or more than the low deviation
alarm value below setpoint, the alarm will become active.
Event based alarms activate when the condition for that alarm type is true. These can be
Signal Break, Low Memory or Loop Alarms.
Rate of Signal Change Alarm is based on the rate of change of the PV. If the rate of change
is greater than the alarm value for longer than the Minimum Duration time, the alarm will
activate. Control Power High and Control Power Low alarms are based on the output power
from the PID control algorithm.
Also refer to: Alarm Operation; Band Alarm Value; Control Deviation; Control Power Alarm;
Deviation Alarm; Loop Alarm; PID; Process High Alarm; Process Low Alarm; Process
Variable; Rate Of Change Alarm; and Setpoint.
Alternate Setpoint
The instrument can use one of two setpoints (Main or Alternate). The alternate setpoint can
be chosen from Local Setpoint 2 or a remote setpoint input from Auxiliary Input A if fitted.
One setpoint can be chosen as the active at using the setpoint selection screen.
Also refer to: Auxiliary Input; Local Setpoints; Main Setpoint; Profiler; Remote Setpoints;
Setpoint and Setpoint Select.
Auto Pre-Tune
When the auto pre-tune is enabled, a pre-tune activation is attempted at every power-up
(Standard Pre-Tune activation rules apply). Auto pre-tune is useful when the process to be
controlled may vary significantly each time it is run. Auto pre-tune ensures that the process is
tuned correctly each time the process is started. Self-tune may also be engaged to fine-tune
the controller.
Also refer to: Pre-Tune; Self-Tune; PID and Tuning.
Automatic Reset
- Refer to Integral Action
Auxiliary Input
A secondary linear input module can be installed in option slot A to provide a remote setpoint
input. Signals can be mA, or VDC. The 2
nd
Universal input can also be used as an auxiliary
input if fitted.
Also refer to: Alternate Setpoint; Digital Input; Linear Input; mADC; Remote Setpoint and
VDC
Auxiliary Input Lower Limit
When auxiliary input A is used to provide a remote setpoint (RSP), this setting defines the
Alternate Setpoint value when the auxiliary input signal is at its minimum value (e.g. for 4 to
20mA, the value when 4mA is applied). However, the setpoint is always constrained by the
setpoint limits.
Also refer to: Alternate Setpoint; Auxiliary Input; Auxiliary Input Upper Limit; Auxiliary Input
Offset; Remote Setpoint; Setpoint and Setpoint Upper Limit and Setpoint Lower Limit.