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(6) Investigation of transmission wave shape/noise
Control is performed by exchanging signals between outdoor unit, indoor unit and remote controller by M-NET trans-
mission. If noise should enter into the transmission line, the normal transmission will be hindered causing erroneous
operation.
1) Symptom caused by the noise entered into transmission line
2) Method to confirm wave shape
Cause Erroneous operation Error code
Noise entered into Signal changes and is misjudged as the signal of other 6600
transmission line address.
Transmission wave shape changes to other signal due 6602
to noise.
Transmission wave shape changes due to noise, and can 6607
not be received normally thus providing no reply (ACK).
Transmission can not be made continuously due to the 6603
entry of fine noise.
Transmission can be made normally, but reply (ACK) or 6607
answer can not be issued normally due to noise. 6608
<with transmission>
<without transmission>
Check the wave shape of transmission line with an oscilloscope to confirm that the following
conditions are being satisfied.
1 The figure should be 104µs/bit ± 1%.
2 No finer wave shape (noise) than the transmission signal (52µs ± 1%) should be allowed.
✻
1
3 The sectional voltage level of transmission signal should be as follows.
✻
1 However, minute noise from the DC-DC converter or inverter operation may be picked up.
Logical value Transmission line voltage level
0VHL = 2.0V or more
1VBN = 1.3V or less
▼
▼
▼
▼
▼
▼
▼
▼
No fine noise allowed
✻
1
V
BN
VHL
52µs52µs52µs52µs52µs
Logical value "0
"
Logical value "1"
No fine noise allowed
✻
1
-
54
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