Trane BACnet BCI-R, Руководство по интеграции

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14 BAS-SVP09B-EN
BCI-R Operation
Periodic Update of BAS Values
The BCI-R device requires the BAS system to provide a periodic update to the sensor values. This
protects against a loss of communication between the BAS and the BCI-R. By BACnet definition,
the present value of the object will maintain the last value written to it, regardless of the amount
of time that has elapsed since the last write. If communication is lost for several minutes or longer,
the present value of BAS-supplied sensor objects may no longer represent the current state of
environmental conditions. This may result in decreased occupant comfort and damage to building
systems.
BAS Communication Failure
The BCI-R is designed to minimize communication failure mode. It does this by monitoring the
length of time that has elapsed since the last write to the present value of the sensor object. If the
length of time exceeds a predefined limit, the BCI-R will place the object into the
fault state and
revert to a unit-supplied sensor value for control. At power up, the sensor objects are set to a fault
state and they will remain in this state until a write is detected.
The minimum periodic refresh rate for the objects is defined in Table 3, p. 24 . The following list is
a set of sensor values that can be supplied by the BAS:
• Space Static Pressure BAS
• Space Air Temperature BAS
• Outdoor Air Temperature BAS
• Outdoor Air Humidity BAS
• Space CO2 Concentration BAS
• Space Humidity BAS
Input/Output Commands and Calculations
This section will provide the following information about certain inputs and outputs that perform
• Filter timer and diagnostic reset commands
• Setpoint calculations
Filter Timer Reset Command
The BCI-R uses the Filter Runtime Hours object (analog input 6) to generate a diagnostic when its
present value is greater than the Filter Runtime Hours Setpoint , (analog value 1) present value. The
procedure for resetting the timer is as follows:
The BAS will change the state of the Filter Timer Reset Comm and object (binary output 13) to
the active state. Upon the change to active state, the BCI-R will set the present value of the Filter
Runtime Hours object to zero and then set the Reset Command object back to the inactive state.
Diagnostics Reset Command
The ReliaTel control system monitors the operation of the HVAC equipment. If an abnormal
condition is detected, an event notification message is sent to the Tracer SC. The corresponding
binary input object will change state from
inactive to active when the diagnostic is detected. The
object has been configured to send a BACnet event message to external BACnet devices as defined
by the protocol.
The BAS has the ability to reset internal diagnostics by controlling the state of the Diagnostic Reset
Command object (binary output 14) as follows:
• The BAS will change the state of the Diagnostic Reset to the active state.
• Upon the change to active state, the ReliaTel control system will reset all internal diagnostics
and set the state of all the diagnostic objects to inactive .