Applications Guide Tracer Graphical Programming - Trane

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Adding a block
7. In the Program Description field, type:
This program controls the equipment room exhaust fan. The fan
turns on when the equipment room temperature is above 85°F.
Note:
To include the degree (°) symbol, press and hold the Alt key
while pressing 0, 1, 7, 6 on the keypad. Then release the Alt
key, and the symbol appears. (Alt+0176)
8. Click OK.
➤ Methods of program execution: Run frequency, event trigger,
and start-up
To select the appropriate method of program execution, ask yourself
the following questions:
• Is the program required to run at regular time intervals? If so,
click the Run Frequency option. Then specify the time interval in
hours, minutes, and seconds.
• Is the program required to run on demand? If so, use the Event
Trigger option to provide the program with a reference, which you
specify, to a universal input configured as a binary input or to a
binary variable. When the binary input or variable changes state,
the program runs. (If the trigger direction, off to on or on to off, is
a concern, you will have to add logic to another program to check
it.)
• Is the program required to run only when the Tracer MP580/581
powers on? In this case, click the Start-up option.
Adding a block
For the program, start with an Input block to access the space temperature
hardware input. Input blocks pass data into the program from hardware
universal inputs.
To add a block:
Programming tip:
Place input blocks on the left and output blocks on the right so
that your program reads from left to right.
1. From the Blocks menu, choose Input/Output. From the Input/Output
menu, choose Input (Hardware). The cursor changes to a cross-hair
(✛) when over the design space.
2. Click in the design space to place the block. The block appears at the
cursor location in the design space (Figure 13 on page 18).
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