Echelon LonMaker User Manual
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Appendix C - QuickStart Exercise
e. Under Logic Function, click Greater Than.
Now, if the value from Analog Input 1 (the temperature) is greater than or equal to the value
from Analog Input 2 (the setpoint), the Digital_Out output network variable on the
thermostat (AFB) functional block will transmit a value of On. After the Digital input
network variable on the fan exhaust switch (DO) functional block receives and processes the
On value, the exhaust fan turns on. If the temperature is less than setpoint, the Digital_Out
network variable on the thermostat (AFB) functional block transmits a value of Off to the
Digital input network variable on the fan exhaust switch (DO) functional block and the fan
shuts off.
f. In the Hysteresis box, enter the hysteresis value, which for this example, is 4.5 for Fahrenheit
or 2.5 for Celsius.
The hysteresis value affects the digital output value. The hysteresis value determines how
great a difference, as a floating-point number, must exist between the network variables
(operands) in the selected function to change the value passed by the digital output network
variable. Using the previous example, the temperature now must be more than 4.5° above the
setpoint (72.5° F or 22.5° C) for the Digital_Out network variable on the thermostat (AFB)
functional block to transmit an On value. Conversely, the temperature must drop more than
4.5° below 72.5° F or 22.5° C for the Digital_Out network variable to transmits an Off value.
g. Click OK.
10. If you physically have the analog input and digital output LonPoint devices, you can monitor the
network variables to verify that the network is functioning properly. You can do this by
monitoring the connections, using the LonMaker Browser, or creating a Data Point shape (see
Chapter 6, Monitoring and Controlling Networks, for how to use each of these network
monitoring tools).
Raise or lower the temperature on the analog input device. The network variable values
representing the temperature should change accordingly. As the temperature rises, the fan
(represented by a LED on the DO-10 device) should illuminate. As the room cools down, the fan
(LED) should turn off.