11-1
CONTROL SYSTEM
SM TRIO52 1-A.2 GB
11. CONTROL
SYSTEM
11. CONTROL SYSTEM
11.1 General Functions and Operating Rules
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 into indoor, MSMP and main outdoor unit controllers. MSMP
is a specific PCB in outdoor unit which serves as a bridge between all indoor units and
outdoor unit. It communicates with the outdoor unit as one indoor unit and communicates
with each indoor unit as one outdoor unit. Each indoor unit will send the request to MSMP
for cooling/heating capacity supply. MSMP will deal with all the requests from indoor units
and send an integral capacity request to outdoor unit. The outdoor unit will 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, MSMP and 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 total heat or cool load felt by all the indoor units.
11.3
Compressor Frequency Control
11.3.1 NLOAD setting
The NLOAD setting is done by each indoor unit controller, based on a PI control scheme.
MSMP will deal with request from each unit and send a synthetical NLOAD to the outdoor unit.
The actual NLOAD to be sent to the outdoor unit controller is based on the calculated LOAD from
MSMP 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
Outdoor unit NLOAD calculation by MSMP
:
°
°
¿
°°
¾
½
°
°
¯
°°
®
¦
127
,
min
1
ODUNomCode
Code
NLOAD
CalcIDU
NLOAD
ODU
n
i
i
i
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
CONTENTS
