Rockwell Automation 1756-OF8H ControlLogix HART Analog I/O Modules - Manual (Page 58)

58 Rockwell Automation Publication 1756-UM533C-EN-P - February 2011
Chapter 4 1756-IF8H HART Analog Input Module
Process Alarms
Process alarms alert you when the module has exceeded configured high or low
thresholds for each channel. You can latch process alarms. These are set at the
following configurable alarm trigger points:
• High high
• High
• Low
• Low low
The values for each limit are entered in scaled engineering units.
Alarm Deadband
You can configure an alarm deadband to work with the process alarms. The
deadband lets the process alarm status bit remain set, despite the alarm condition
disappearing, as long as the input data remains within the deadband of the
process alarm.
The figure below shows input data that sets each of the alarms at some point
during module operation. In this example, Latching is disabled; therefore, each
alarm turns OFF when the condition that caused it to set returns to normal.
Table 4 - Input Data That Sets Each Of the Alarms
43153
High high
Low low
Low
High
Alarm deadbands
High high alarm turns OFF
High alarm remains ON High high alarm turns ON
High alarm remains ON
Normal input range
Low low alarms turns OFF
Low alarm remains ON
High alarm turns OFF
Low low alarms turns ON
Low alarm remains ON
Low alarms turns OFF Low alarms turns ON
High alarm
turns ON