Mitsubishi Electric CITY MULTI PUHY-P108 Service Handbook page 325

[ IX Troubleshooting ]
2. MA remote controller transmission
The communication between the MA remote controller and the indoor unit is performed with current tone burst.
(1) Symptoms caused by noise interference on the transmission line
If noise is generated on the transmission line, and the communication between the MA remote controller and the indoor
unit is interrupted for 3 minutes in a row, MA transmission error (6831) will occur.
(2) Confirmation of transmission specifications and wave pattern
A1
B2
MA remote controller
Transmission waveform (Across terminal No.1 - 2)
Logic 1
12msec
TB15
Indoor unit
Logic 0 Logic 1 Logic 1
12msec 12msec 12msec
- 316 -
1
A1, B2 : No polarity
2
Across terminal No. 1-2
: Power supply (8.5V to 12VDC)
Satisfies the formula
12 msec/bit
DC9~12V
Voltage among terminals must
be between DC9 and 12 V.
5%