Mitsubishi Electric PKA-RP1.6GAL Service Technical Manual page 36

(4) The waveforms of communications between indoor and outdoor units
The following graphs are the examples for measuring waveforms on the wirings of connecting indoor and outdoor units at
between S2 and S3 of the outdoor terminal block TB1.
a) A measuring example the sequence of startup: 1
Transmission Transmission
from
from
indoor unit outdoor unit
10V/div, 500msec/div:
c) A measuring example during normal stop
(When one outdoor unit connects one indoor unit)
Transmission Transmission
from from
indoor unit
outdoor unit
10V/div, 500msec/div:
c) Expanded waveform
10V/div, 50msec/div:
• During normal operation, outdoor unit interactively exchanges signals with all the connected indoor units.
• When outdoor unit cannot receive signals for three minutes from an indoor unit due to any trouble like cable disconnection, it
is considered as abnormal and the outdoor unit stops. E8 is displayed on the remote controller. This is to avoid independent
operation of indoor units.
b) A measuring example in the sequence of startup: 2
Transmission Transmission
from
from
indoor unit outdoor unit
10V/div, 500msec/div:
d) A measuring example during normal stop
(When one outdoor unit connects two indoor units)
Transmission
from
one indoor unit
Transmission
from
indoor unit
10V/div, 500msec/div:
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Transmission
from
another
indoor unit