Panasonic S-M20PY3E Installation Instructions Manual page 30

(2) Do not install the inter-unit control wiring in a way that forms a loop.
Outdoor unit
Indoor unit
(3) Do not install inter-unit control wiring such as star branch wiring. Star branch wiring
causes mis-address setting.
Outdoor unit
NO
(4) If branching the inter-unit control wiring, the number of branch points should be 16
or fewer.
The setting of the terminating resistance changes according to the number of refrigerant
systems connected to the integrated control wiring in the link.
• For one refrigerant system in the link wiring, it is necessary to set one terminating
resistance to the valid (SHORT side). For over 2 refrigerant systems, it is necessary to set 2
terminating resistance to the valid (SHORT side).
• The valid or invalid setting of the terminating resistance is basically carried out with the
outdoor unit. However, 3-line connection outdoor unit cannot make a setting of terminating
resistance. In this case, the shortage of the valid setting for the terminating resistance
should be carried out with the indoor unit. The setting of the terminating resistance of the
2-line outdoor unit at shipment is the valid (SHORT side) and indoor unit is the invalid
(OPEN side).
● In case that the inter-unit control wiring in the link are all 3-line connection:
Outdoor unit
Indoor unit Indoor unit
Indoor unit
Indoor unit
Outdoor unit
Outdoor unit
Outdoor unit
Outdoor unit
Prohibited
Indoor unit
Indoor unit
Indoor unit
Branch point
Central Controller
Indoor unit
Indoor unit
Indoor unit
30
Prohibited
Indoor unit
Indoor unit Indoor unit
Indoor unit Indoor unit