Applications Guide Tracer Graphical Programming - Trane

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Writing the alarms module
In this application, when the output of the Less Than block is true, the
delay timer begins counting down. If the output of the Less Than block
remains true throughout the delay time, when the delay timer expires,
the output of the Delay on Start block becomes true as well.
To time the sump temperature alarm:
1. From the Blocks menu, choose Time Delay. From the Time Delay
menu, choose Delay on Start.
2. Click in the design space to place the Delay on Start block.
3. Set the Delay on Start block delay time units to minutes.
4. Add a Constant block to the design space and assign the value 15.0 to
it to represent the delay time.
5. Connect the Less Than block to the On/Off Control port of the Delay
on Start block.
6. Connect the 15.0 constant block to the Delay port of the Delay on
Start block (Figure 54).
Figure 54: Implementing the Delay on Start block
Controlling the sump temperature alarm
The requirement calls for the program to turn on the alarm output when
the “sump temperature remains below 36°F (this value is adjustable at
the operator display) for 15 minutes, or if the sump temperature falls
below 32°F.” Use an Or block to complete the picture, connecting the
Delay on Start and the Less Than or Equal blocks to the Or block. Then
connect the Or block to the Alarm output block. The result is pictured in
Figure 55 on page 58.
To control the sump temperature alarm:
1. Place an Or block in the design space.
2. Connect the Delay on Start block and the Less Than or Equal block to
the Or block.
3. Connect the Or block to the Alarm output block (Figure 55 on
page 58).
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