Applications Guide Tracer Graphical Programming - Trane

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Chapter 2 Writing the exhaust fan program
Blocks
You will learn how to use the following blocks:
• Input (Hardware)
• Constant
• Output (Hardware)
• Greater Than
• Comment
Reviewing the sequence of operation
To begin, review the sequence of operation to determine the necessary
data definitions, such as the inputs, outputs, and variables. Then draw a
wiring diagram.
In this scenario an equipment room contains machinery that generates a
significant amount of heat. As a result, the temperature in the room rises.
When the temperature exceeds 85°F, turn on the exhaust fan to draw outside
air through the equipment room. When the temperature falls below
85°F, turn off the exhaust fan.
Analyze the scenario and its sequence of operation to determine the necessary
inputs, outputs, and variables. Analyzing this scenario might
result in Figure 10.
Figure 10: Equipment room exhaust fan data
A temperature sensor in the room supplies the space temperature as an
analog value, so you need an analog input to read the temperature.
Because the exhaust fan is either on or off, use a binary output to control
the fan. The resulting data definition is presented in Table 2 on page 13,
and a wiring diagram is presented in Figure 11 on page 14.
Before you start to write the program, configure the inputs and outputs
as shown in Table 2 on page 13. For more information on setting up the
wiring, see the Tracer MP581 Programmable Controller Hardware Installation
guide (CNT-SVN01A-EN). For more information on configuring the
12 CNT-APG001-EN