Considerations On Temperature Registers - HMS Networks Intesis INMBSDAI001I000 User Manual

Modbus Registers

5.2.3. Considerations on Temperature Registers

• AC unit temperature setpoint (R/W) (protocol address register 4 / PLC address register 5)
This is the adjustable temperature setpoint value required by the user. This value can be read and written. A
remote controller connected to the Daikin indoor unit will report the same temperature setpoint value as this
register. This will only apply when no AC unit external temperature reference is provided from the gateway.
See AC unit external temperature reference (Modbus) (R/W) below for more information.
• AC unit temperature reference (R) (protocol address register 5 / PLC address register 6)
This register reports the temperature currently used by the Daikin indoor unit as a reference for its control
loop. Depending on the indoor unit configuration, this value can be the temperature reported by the sensor on
the return path of the Daikin indoor unit or the sensor in its remote controller. This value is read-only.
• AC unit external temperature reference (Modbus) (R/W) (protocol address register 22 / PLC address register
23)
This register is used to provide an external temperature value from the Modbus side. The Daikin indoor unit
does not allow to provide a temperature directly to the gateway to be used as a reference for its own control
loop. To overcome this limitation and enable the usage of an external temperature sensor from the Modbus
side when this register is set, the gateway applies the following mechanism, called "virtual temperature":
– Virtual Temperature
After a couple of values have been entered in the AC unit external temperature reference (register
22/23) and the AC unit temperature setpoint (register 4/5), the INMBSDAI001I000 gateway estimates the
appropriate setpoint correction to be applied.
TIP
EXAMPLE: If a temperature setpoint value of 22°C and an external temperature reference value
of 20°C are received (registers 4/5 and 22/23, respectively), the INMBSDAI001I000 gateway will
assume that the user is demanding a +2°C increase in temperature.
By knowing at any time the AC unit temperature reference currently used by the indoor unit to control its
operation (register 5/6), the gateway can calculate the temperature setpoint correction required to reach
the temperature requested by the user.
TIP
In the example given above, if the gateway reads an AC unit temperature reference (register
5/6) of 24°C in the indoor unit, it will apply a final setpoint of 24°C + 2°C = 26°C.
Once set, every time the gateway detects a change in the room temperature reported by the indoor unit
(register 5/6), it will adjust the setpoint accordingly.
TIP
Following the previous example, if the gateway receives a new temperature value (register 5/6)
of 25°C from the indoor unit, the effective setpoint will be adjusted to 25°C + 2°C =27°C.
NOTE
The gateway constantly applies the following virtual temperature formula:
S =T -(T
AC AC BMS
where
S : AC setpoint: Setpoint temperature in the AC system.
AC
T : AC temperature: Ambient temperature in the AC system (AC reference temperature).
AC
T : BMS temperature: Ambient temperature set by the user from the BMS protocol.
BMS
S : BMS setpoint: Setpoint temperature set by the user from the BMS protocol.
BMS
USER MANUAL Version 1.0.0
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BMS
INMBSDAI001I000 Modbus RTU Gateway
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