MH-RC-MBS-1
User’s Manual r6.
3 EN
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11/23
4.2.3
Considerations on Temperature Registers
•
AC unit temperature setpoint (R/W)
(register 4
–
in Protocol address / register 5
–
in PLC address):
This is the adjustable temperature setpoint value that must be required by the user. This
register can be read (Modbus function 3 or 4) or written (Modbus functions 6 or 16). A
remote controller connected to the Mitsubishi Heavy Industries indoor unit will report the
same temperature setpoint value as this register, but only will happen when no AC
unit´s external reference is provided from MH-RC-MBS-1 (see detail for register 22/23
below).
•
AC unit temperature reference (R)
(register 5
–
in Protocol address / register 6
–
in PLC address):
This register reports the temperature that is currently used by the Mitsubishi Heavy
Industries indoor unit as the reference of its own control loop. Depending on the
configuration of the indoor unit, this value can be the temperature reported by the
sensor on the return path of the Mitsubishi Heavy Industries indoor unit or the sensor of
its remote controller. It is a read-only register (Modbus functions 3 or 4).
•
AC unit external temperature reference (Modbus) (R/W)
(register 22
–
in Protocol address / register 23
–
in PLC address):
This register allows us to provide
an external temperature’
s sensor from the Modbus
side. Mitsubishi Heavy Industries indoor unit does not allow on devices like MH-RC-MBS-
1 to provide directly temperature to be used as a reference of the control loop of the AC
indoor unit. In order to overcome this limitation and enable the usage of an external
temperature sensor (i.e.from Modbus side), MH-RC-MBS-1 applies the following
mechanism (
only if “external
temperature
’s
reference
” is being used):
o
After a couple of values have been
entered in the “AC unit external
temperature
’s
reference
” (register 22/23) and “AC unit temperature set
point” (register 4/5
),
MH-RC-MBS-1 is going to estimate the temperature chosen implied (e.g. if a
“temperature setpoint (register
4/
5)” of
22ºC
, and an
“external temperature
reference (register 22/
23)” of
20ºC
are entered, MH-RC-MBS-1 will assume that
the user is demanding a
+2ºC
increase in temperature).
o
By knowing at any time the ambient temperature currently used by the indoor
unit to control its own operation (register 5/6), MH-RC-MBS-1 can calculate the
required temperature setpoint needed to apply the decrease/increase on the real
temperature and reach the temperature chosen by the user (following the
example above, if MH-RC-MBS-
1 reads an “ambient temperature” (register
5/6)
of
24ºC
in the indoor unit, it will apply a final setpoint of
24ºC + 2ºC = 26ºC
).
o
At this moment, each time that MH-RC-MBS-1 detects a change on the ambient
temperature reported by the indoor unit (register 5/6), it will also change the
required setpoint, in order to keep the temperature required by the user at any
time. If we follow the last example, if MH-RC-MBS-1 receives a new
temperature´s value coming from the indoor unit of
25ºC
, MH-RC-MBS-1 will
automatically adjust the temperature setpoint required of the AC indoor unit to
25ºC + 2ºC = 27ºC
).
o
In general, MH-RC-MBS-1 is constantly applying
the “
Virtual Temperature
”
formula:
S
AC
=
S
u
– ( T
u
– T
AC
)
