ACC-SVN100A-EN • LonTalk Communication Interface 45
Network Variable and Configuration Property Definitions
• When Transmitted: nvoStatus is transmitted whenever a request is received on the
nviRequest input and as one of the heartbeat nvos. The node object status is sent
during the first heartbeat nvoStatus transmission. Then the chiller object status is
sent during the second heartbeat nvoStatus transmission, depending on which
profile is being used. And then the cycle repeats.
• Update Rules: The application must update the status such that a poll of the status
following the request returns the most recent data.
• Update Rate: Send heartbeat time
• Default Service Type: Unacknowledged
nvoStatusOutputs
Status outputs, SNVT_state
This variable is used to relay state information about the chiller. Max Capacity provides
an indication that all available chiller capacity is being used. When the Head Relief
Request bit is set, the chiller is asking an outside system to provide more heat rejection
from the condenser water loop. Additional heat rejection creates lower condenser water
loop temperatures, which lowers the condenser refrigerant pressure (head). Base
Loading Active indicates whether the Base Loading control method is currently being
used. Hot Gas Bypass Active is set when Hot Gas Bypass is being performed by the
chiller. Noise Reduction Active is set when the chiller is in a state where the noise is being
reduced. The efficiency of the chiller may be reduced in this mode. In Defrost indicates
that one or more circuits on the chiller are in a defrost mode.
Structure definition
Bit position Description
Bits 0–7 Validity of bits 8–15 (1 = valid)
Bit 8 Max Capacity (1)
Bit 9 Head Relief Request (1)
Bit 10 Base Loading Active (1)
Bit 11 Hot Gas Bypass Active (1)
Bit 12 Noise Reduction Active (1)
Bit 13 In Defrost (1)
Bits 14–15(LSB) Not Used
