Haier H2SM Series Service Manual page 15

The outdoor unit waits to receive signal HEADER HDR(81H) from the indoor unit after the power
supply inputs. When transmitting signal, HEADER is C3H. When a signal is first transmitted at the
head, data "1" outputs HI of 9MS and LO of 2MS and data "0" outputs HI of 2MS and LO of 9MS.
When receiving signal, the signal reception is carried out depending on the majority of the 5
th
and 7 5,6,7MS.
The signal reception will not take place until a correct HDR signal is received.
Output 1:
0:
Input 1:
0:
2.2. Checkout of errors
The signal reception does not take place until the outdoor unit receive signal HDR from the indoor
unit. At the completion of the signal reception, the data is compared with the inverter data. When
incorrect, all the data is given up. If it is incorrect in 20 seconds of comparison, the compressor,
4-way valve and outdoor fan turn off, giving the abnormal condition and sending out the
corresponding error codes for the abnormalcy of signal delivery and transmission.
2.3. Timer for communication data input /output
After the power supply inputs, the outdoor communication output is HI, waiting for the indoor unit
to send signal.
The timer counter is cleared 0 at the decline of communication, regarding 3 times of 5,6,7 ms.
The status of the communication input PORT determines input signals. When in the next decline of
communication, the timer counter is cleared one again.
HEADER 8 bits, the data and inverter data 48 bits, and the total is 56 bits. After the data has been
received, LO of 10 ms is ready to send signal. The 0 clearance of the timer counter during the
sending takes place in a 1 ms interruption.
HEADER 8 bits, the data and inverter data 48 bits, and the total is 56 bits. After the data has been
sent, Both output LO of 5 ms and output HI of 5ms are ready to receive signal 4 and
communications
Air Conditioner
9ms 2ms
11
Edition:2006/1/10
th th
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