Fault Tolerance - Honeywell CVL4022ASVAV1 Engineering Manual

NOTE: a: nvoError and nciAlarmInhibit are implemented
as arrays of bytes. Each bit refers to a specific
error and is identified by the bit position. For
example Bit position 20 means the 4th bit in the
3rd byte of the array. Similar bit position 0 means
the first bit of the first byte.
FAULT HANDLING IN THE CONTROLLER

Fault Tolerance

The controller handles specific error conditions as described
below
Error Condition
Space Temp Error
SetPt Error
Dischg Temp Error
Supply Temp Error
airflow Error
nviSpaceTempError
nviApplicModeError
nviSetPoint
nviWindow Error
nviiSupplyTemp Error
nviDlcShed Error
nviTodEvent Error
nviBypass Error
nviOccCmd Error
nviFlowTrack Error
nviFlowOffset Error
nviFree1Dig Error
nviFree1Mod Error
31-00083—02
Table 14. Fault Tolerance
Alarm
SensorFailed Temperature control is turned off and the damper is set to either a minimum
Position or closed depending on the EffectOcc, Mode, and FlowControlType. Fan
operation is not affected.
nviShare can be used as a fall back strategy for a Wall Module space
temperature sensor failure. FlowControlType must be normal. When the space
temperature sensor fails, the master VAV controller will take over control of the
satellite VAV (controller with failed space temperature sensor).
SensorFailed Uses default occupied Set Points
SensorFailed None
SensorFailed Supply temperature is taken out of the Mode arbitration logic.
SensorFailed When the mode is Cool, the damper is modulated between 15% and 60%. When
the mode is ReHeat, the damper is set to a calculated value.
nvoFlowTrack = 0 + nviFlowTrack
CommFailed Network variable is set to the FD value
CommFailed Network variable is set to the FD value
CommFailed Network variable is set to the FD value
CommFailed Network variable is set to the FD value
CommFailed Network variable is set to the FD value
CommFailed Network variable is set to the FD value
CommFailed Network variable is set to the FD value
CommFailed Network variable is set to the FD value
CommFailed Network variable is set to the FD value
CommFailed Network variable is set to the FD value
nvoFlowTrack = measuredAirflow + 0
CommFailed Network variable is set to the FD value
CommFailed Network variable is set to the FD value
CommFailed Network variable is set to the FD value
NOTE: b: To communicate successfully with an Asc VAV
device, TR71/TR75 devices must be configured
with the address 1 and the C7400S sensor must
be configured with the address 8.
Control Action
38