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Application
feature
Factory default status
Heating coil
Coil preheat
Frost protection
Default temperature setpoint
On
On
40 deg. C
Floor heating
Floor overheat protection
Default temperature setpoint
On
40 deg. C
Radiator heating
Default temperature setpoint
40 deg. C
Cooling applications
Frost protection
Default setpoint
On
15 deg. C
Table 1: Application specific factory default values.
3
CONFIGURATION OF SETPOINTS AND BUS CONTROL
The field bus profile for MIXIT is made such that for the commands that can be given on an output
object/register, there is a corresponding input object/register for reading back that the command was
registered. The integration of MIXIT via the field bus protocols can only work if:
•
MIXIT is set for bus control, otherwise it will not react on commands and setpoints. The bus control
state is not persistent if the communication fails or MIXIT experience at power cycle. Therefore,
there must be a cyclic checking and setting in case it has fallen back to local control.
•
The correct setpoint chain is configured. For BUS control this is a persistent configuration and shall
only be set once.
The configurations are described by Table 2.
Action
BACnet
Modbus
Persistent setting
Object for
setting
Object for
status
Register for
setting
Register for
status
Config. set-
point from
fieldbus
MV,0 = 3
MV,0
00117 = 2
00117
Yes
Set setpoint
from fieldbus
AO,0
AI,0
00102
00311
No
Set bus control
state
BO,0 = 1
BI,0
00101.0 = 1
00201.0
No
Config. default
setpoint
AV,6
AV,6
00118
00118
Yes
Set start/stop
BO,1
BI,2
00101.1
00201.3
No
Table 2: Configuration and setting of remote state.
If MIXIT experience a communication failure, it will use the default setpoint which is factory configured at
40 deg. C for heating applications and 15 deg. C. for cooling applications. Therefore, it is a good idea to
configure with a value meaningful for the application.
Notice!
The default setpoint (BACnet: AV,6 / Modbus: 00118)
is a persistent datapoint and shall not be
used for regular/cyclic setpoint control. It is a fall back setpoint in case bus communication fails.
Notice!
Single bits in Modbus register 00101 cannot be addressed even though the description of the
register in the Modbus profile is bitwise. When writing the register all bits in the register must be written to
their desired values.
