Data format alarm example, Overrange alarm, Underrange alarm – Rockwell Automation 1797-OE8 FLEX Ex Analog Modules User Manual User Manual

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Publication 1797-6.5.1 - May 2005

1-4 About the FLEX Ex Analog Modules

Data Format Alarm Example

In this example, the normal active data range is 4-20mA. The alarms are
generated in three overlapping bands.

Overrange Alarm

The Overrange alarm notifies you when module input is overrange. When the
input signal exceeds 100% (20mA), an Overrange Alarm is generated.

This alarm stays active at any value above 100% of range and is always enabled
by the module.

Underrange Alarm

The Underrange alarm works in a fashion converse to the overrange. This
feature notifies you when the input signal falls underrange. If the input signal
falls below 0% (4mA), an Underrange Alarm is generated.

This alarm stays active at any value below 0% of range and is always enabled by
the module.

PHYSICAL INPUT SIGNAL RANGE

0mA

4mA

20mA

22mA

remote fault

remote fault

local
fault

local
fault

underrange

overrange

programmable

in 20 0.1mA

steps by Error

Level 0.1mA

Steps

parameter

-12.50%

0.00%

-25.00%

Remote Transmitter Error

Up/Down parameter

determines which of these

is active

programmable

in 20 0.1mA

steps by Error

Level 0.1mA

Steps

parameter

100.00%

112.50%

41666

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