6. Programming Notes
DCM014A51
Quick User Guide
11
6.9 Priority array
1. An object in the iTM BACnet® Server Gateway has a priority array, so that the highest priority value
would be sent to the indoor unit.
2. The indoor unit does not have priority. The last change would be valid in the indoor unit from either the
iTM BACnet® Server Gateway, iTM, or remote controller.
6.10 Restrictions
1. When a Present Value (PV) is set by the BMS, the iTM BACnet® Server updates the PV and keeps the
previous PV.
2. The iTM BACnet® Server sends the new PV to Management Point in the iTM. The iTM BACnet® Server
then starts a 10-min timer.
3. If the value in Management Point is changed (which means the indoor unit accepted the new value and
sent back the new status to the iTM), the Management Point in the iTM sends the new value to the iTM
BACnet® Server. The iTM BACnet® Server updates the PV and reset the 10-min timer.
4. If the value in Management Point is not changed (which means the indoor unit did not accept the new
value and failed to update the status to the iTM), then nothing happens. Once the 10-min timer expires,
the iTM BACnet® Server resets to the previous PV.
Restriction Examples
EXAMPLE 1 - Cool SP max
Step
BMS
BACnet® Server in ITM
Management Point in ITM
Pre-condition
•
Unocc Cool SP: 80°F
•
Cool SP range: 70-76°F
•
Cool Setback SP: 80°F
•
Cool SP range: 70-76°F
#1
•
Sets Cool SP max 85°F
•
PV: 85°F
, previous PV: 76°F
•
Start 10-min timer
#2
•
Sends 85°F to Management Point
•
Cool SP max 85°F is rounded to 78°F due to
Cool Setback SP 80°F.
•
Cool SP range: 70-
78°F (Changed)
#3
•
PV 78°F
•
Reset 10-min timer
•
Updates 78°F to the BACnet® Server
#1
•
Sets Cool SP max 85°F
again
•
PV: 85°F
, previous PV: 78°F
•
Start 10-min timer
#2
•
Sends 85°F to Management Point
•
Cool SP max 85°F is rounded to 78°F due to
Cool Setback SP 80°F
•
Cool SP range: 70-78°F (No change)
#3
•
When 10-min timer expires, PV back
to 78°F
