Rockwell Automation FactoryTalk View Machine Edition Users Guide - Manual (Page 132)

F ACTORY T ALK V IEW M ACHINE E DITION U SER ’ S G UIDE
9-12
• •
•
•
•
if ((Acid_tank_level > 74) AND (Acid_tank_level < 90))
then 1
else if (Acid_tank_level > 89)
then 2
else 0
2. Use the Value trigger type for the alarm trigger.
3. Specify these trigger values and alarm messages for the alarm trigger:
At run time, when the value of Acid_tank_level is 75 or greater, FactoryTalk View
generates the first alarm message. The second message is generated when the tag value is
90 or greater.
Using the expression in step 1 allows a range of values to trigger each alarm. This is
useful in case the tag is not being read at the exact moment it reaches a threshold level.
The Bit trigger type
Use the Bit trigger type to generate multiple simultaneous alarm messages. You can assign
an array tag (consisting of up to 1,024 bits) to the trigger connection. Each bit in the array
whose value changes from 0 to 1 triggers an alarm (if a message is set up for the bit
position).
Example: Trigger values using bit positions
This example shows how to use bit positions to generate multiple simultaneous alarms.
The array tag uses 32 bits, from N7:0/00 to N7:1/15.
This diagram shows the bit addresses and bit positions for the array tag:
Trigger Value Message
1 Warning! The acid tank has exceeded safe fill levels.
2 Danger! The level in the acid tank is too high.