11-1
CONTROL SYSTEM
SM DUO38I 1-A.2 GB
11. CONTROL
SYSTEM
11.1
General Functions and Operating Rules (for single split
models)
The DCI software is fully parametric.
All the model dependent parameters are shown in Blue color and with Italic style
[
parameter
].
The parameters values are given in the last section of this control logic chapter of the
service manual.
11.2
System Operation Concept
The control function is divided between indoor and outdoor unit controllers. Indoor unit is the
system ‘Master’, requesting the outdoor unit for cooling/heating capacity supply. The outdoor
unit is the system ‘Slave’ and it must supply the required capacity unless it enters into a
protection mode avoiding it from supplying the requested capacity.
The capacity request is transferred via indoor to outdoor communication, and is represented
by a parameter called ‘NLOAD’. NLOAD is an integer number with values between 0 and
127, and it represents the heat or cool load felt by the indoor unit.
11.3
Compressor Frequency Control
11.3.1 NLOAD
setting
The NLOAD setting is done by the indoor unit controller, based on a PI control scheme.
The actual NLOAD to be sent to the outdoor unit controller is based on the preliminary
LOAD calculation, the indoor fan speed, and the power shedding function.
NLOAD limits as a function of indoor fan speed:
Indoor Fan Speed Maximum NLOAD Cooling
Maximum NLOAD Heating
Low
Max NLOADIF1C
127
Medium
Max NLOADIF2C
127
High
Max NLOADIF3C
127
Turbo
Max NLOADIF4C
127
Auto
Max NLOADIF5C
127
NLOAD limits as a function of power shedding:
Mode
Power Shedding OFF
Power Shedding ON
Cool
No limit
Nominal Cooling
Heat
No limit
Nominal Heating
