Troubleshooting; Data Communication Errors; Data Communication Continue Error - Mitsubishi MELSEC-A AJ71PT3 User Manual

6. TROUBLESHOOTING
IMELSEC;4
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6. TROUBLESHOOTING
6.1 Data Communication Errors
There are two types of errors which may occur during data
communication between the master module and remote 1/0
stations.
(1) Error which only stops data communication with the faulty
remote 1/0 station.
(2) Error which stops data communication with all remote 1/0
stations.
REMARKS
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A communication error indicates that normal communication could not be made
after retries had been made the number of retries set to buffer memory address 1.
6.1.1 Data communication continue error
The following operations are performed when the error occurring
only stops communication with the faulty station and continues
communication with the other stations:
(1) Switches on X6 (MINI link error detection).
X6 is switched off when communication is restored. For
further details, see Section 3.3.
(2) Stores the faulty station number to buffer memory addresses
100-103.
(a) Sets 1 to the corresponding bit.
(b) In automatic return mode, the corresponding bit is reset to
o
when the faulty station is restored.
(c) In no automatic return mode, the corresponding bit
remains 1.
(3) Stores the accumulative faulty station numbers to buffer
memory addresses 90-93. This area stores the accumulative
result of faulty stations explained in Para. (2).
(4) Stores the error detection code in buffer memory address 108.
1 is written to this address when any station causes a
communication error. 1 remains if communication is restored .
(5) Clears the faulty station, accumulative faulty station and error
detection code when Y18 is switched on.
(6) Switches on the "ERR. REM" LED of the master module.
(7)
Switches off all outputs of the faulty station in no automatic
return mode.
POINT
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The data communication continue error may occur when:
(1) The remote 1/0 stations connected do not coincide
with the number of remote 1/0 stations (address 0)
specified.
For example, an error occurs at station 3 when the
number of stations set is 5 and there are stations 1, 2, 4
and 5 connected.
(2) The fuse in an output remote 1/0 station has blown.
(3) A communication data error has occurred due to noise.
In this case examine the data link cable wiring and
ground methods.
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