4.3 Alarms

Alarms are used to alert an operator when a pre-set level has been exceeded. They are indicated by flashing the alarm number and the red ALM beacon in the display.

 

Up to three process alarms may be configured using ‘P’ Codes P21 to P29.

 

They may also switch an output, usually a relay, to allow external devices to be operated when an alarm occurs (‘P’ code P11 to P14).

 

☻ ‘P’ codes are found in section 5.2.

 

Each alarm can be configured to the types listed below:

 

Alarm Type	Description
Full Scale Low	The alarm is shown if the process value falls below an absolute threshold
Full Scale High	The alarm is shown if the process value rises above an absolute threshold
Deviation Low	The alarm is shown if the process value deviates below the setpoint by a set threshold
Deviation High	The alarm is shown if the process value deviates above the setpoint by a set threshold
Deviation Band	The alarm is shown if the process value deviates above or below the setpoint by a set threshold

 

In addition to the above alarms the following alarm types may be configured:-

 

Sensor Break	If the sensor becomes open circuit the alarm message Sb.r is flashed in the display. The controller control outputs can be configured to output a ‘safe’ value. ( ‘P’ code P36).
Excess Current	An alarm will be indicated if the current is exceeded. (‘P’ code P33). Current alarms can be Load, Leakage, Overcurrent
Loop Break	The loop is considered to be broken if the PV does not respond to a change in the output in a given time. (‘P’ code P34).

 

If an alarm is not configured it is not shown in the list of level 2 parameters shown in section 4.6.2.