Mitsubishi Electric PUHY-P250YNW-A Service Handbook page 107

[5-2 Outdoor Unit Control ]
(1) Rotation Group Setting
Group setting is required to enable the system rotation control function.
Group setting must be made after the setup sequence for all applicable indoor and outdoor units have been completed.
By turning the Dip SW4 (930) from OFF to ON on the outdoor unit with the lowest odd number address in a given group while
the unit is stopped, this unit is designated as the control unit.
The control unit sends signals to other units with the addresses that equals "the control unit address + 2, +4, +6, +8" in this
order and includes the units that returned the response signal in the group.
If there is a unit that does not return a response signal or if a response is returned that indicates another unit is designated as
a control unit, communication and group setting will be completed.
Group setting pattern will fall into one of the following 9 patterns as shown in Figure 3. In patterns 5 and 9, only the control
unit will be designated, but this function will not be used.
In patterns 6 through 9, the second CU and on will be in another group.
Pattern 1
Pattern 2
Pattern 3
Pattern 4
Pattern 5
Pattern 6
Pattern 7
Pattern 8
Pattern 9
A: Odd numbers between 51 and 91
CU: Control unit
(2) Starting Conditions
This control function is initiated after group settings have been made and if all of the following conditions are met.
Initial setup sequence for all the units in the group has been completed.
All the units in the group are in operation.
No errors are detected by any unit in the group.
(3) Rotation Operation
When the above starting conditions are met, the control unit will bring the backup unit to stop, and the system rotation timer
starts counting.
When the system rotation timer reaches 480 hours, units are rotated to become the backup unit.
When rotation is performed, first the stopped backup unit is started, then the system rotation timer is reset, and finally the next
backup unit is brought to stop in three minutes or less.
The address of the unit that is currently designated as the backup unit can be found by setting Dip SW4 on the outdoor unit
that is designated as the control unit as shown below.
ON
2 3 4 5 6 7 8 9 10
1
(4) End Conditions
This control function is terminated by turning the Dip SW 4 (930) from ON to OFF on the control unit (outdoor unit) while the
unit is stopped.
When this function is disabled, the group setting information and the system rotation timer on the control unit will be cleared.
If any backup unit other than the control unit is stopped as a backup unit, that unit will automatically resume its operation.
18
- chapter 5
Outdoor unit addresses
A A+2
CU
CU
CU
CU
CU
CU
CU
CU
CU CU
: Response returned
Figure 3 Group patterns
SW4
ON
1 2 3 4 5 6 7
The figure at left shows that the switches 1 through 5 are set to ON and 6 through 10 are set to OFF.
A+4 A+6
CU
CU
: No response
SW6-10: OFF
ON
8 9 10 10
A+8
CU
: Optional
BS_05_C