Investigation Of Transmission Wave Shape/Noise - Mitsubishi Electric PURY-P72 Service Handbook
Hide thumbs
Also See for PURY-P72:
- Service handbook (403 pages) ,
- Service handbook (404 pages) ,
- Service handbook (200 pages)
Table of Contents
[ IX Troubleshooting ]
[3] Investigation of Transmission Wave Shape/Noise
1. M-NET transmission
Control is performed by exchanging signals between the outdoor unit and the indoor unit (ME remote controller) through M-
NET transmission. Noise interference on the transmission line will interrupt the normal transmission, leading to erroneous op-
eration.
(1) Symptoms caused by noise interference on the transmission line
Cause
Signal is transformed and will be misjudged as the
signal of another address.
Transmission wave pattern is transformed due to
the noise creating a new signal
Transmission wave pattern is transformed due to
Noise interference on
the noise, and will not be received normally leading
the transmission line
to no acknowledgement (ACK).
Transmission cannot be performed due to the fine
noise.
Transmission is successful; however, the acknowl-
edgement (ACK) or the response cannot be re-
ceived normally due to the noise.
(2) Wave shape check
[With transmission]
[Without transmission]
Wave shape check
Check the wave pattern of the transmission line with an oscilloscope. The following conditions must be met.
1) Small wave pattern (noise) must not exist on the transmission signal. (Minute noise (approximately 1V) can be generated by
DC-DC converter or the inverter operation; however, such noise is not a problem when the shield of the transmission line is
grounded.)
2) The sectional voltage level of transmission signal should be as follows.
Logic
Voltage level of the transmission line
0
1
HWE09130
Erroneous operation
V
HL
V
BN
52
52
52
52
Logic "0"
Logic "1"
No fine noise allowed
V
= 2.5V or higher
HL
V
= 1.3V or below
BN
- 285 -
Error code
6600
6602
6607
6603
6607
6608
No fine noise
allowed
52
Error code definition
Address overlap
Transmission pro-
cessor hardware er-
ror
No ACK error
Transmission line
bus busy error
No ACK error
No response error
GB
Hide quick links:
Table of Contents
Troubleshooting
