Applications Guide Tracer Graphical Programming - Trane

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Chapter 8 Constant-volume AHU with warm-up, pre-cool, and communications
Figure 180: Transmitting the effective setpoint
Use the nvoEffectOccup network variable output to send the effective
occupancy to the building automation system (Figure 181).
Figure 181: Transmitting effective occupancy
The remaining items that must be communicated to the building automation
system include the following:
• Supply fan status
• Cooling valve status
• Heating valve status
• Outdoor air damper status
• Alarm status
• Application mode
One network variable output exists that may be used to communicate all
of the above information. This network variable output, nvoUnitStatus,
consists of a variety of information defined by its type,
SNVT_hvac_status. This particular standard network variable type
(SNVT) is a structure because it contains a variety of elemental variables
of different types within one larger variable. Specifically, nvoUnitStatus
contains the information shown in Table 29.
Table 29: SNVT_hvac_status structure contents
Element SNVT Notes
Mode hvac_t Enumerated
Primary heat output SNVT_lev_percent From –163.83% to 163.83%
Secondary heat output SNVT_lev_percent From –163.83% to 163.83%
Cool output SNVT_lev_percent From –163.83% to 163.83%
Econ output SNVT_lev_percent From –163.83% to 163.83%
Fan output SNVT_lev_percent From –163.83% to 163.83%
In alarm Boolean Alarm status, 0 or 1
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