Mitsubishi MELSEC QJ71C24, User Manual

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MELSEC-Q
11 TROUBLESHOOTING
11.3.7 Communication error "NAK"
Symptom Cause Corrective action MC
Bidirectional
N
on
procedure
Pre-defined
• See section that describes
the communication error
signal ("C/N", "P/S",
"PRO", "SIO") that are
turned on simultaneously
when the "NAK" signal is
turned on.
• Take corrective action corresponding to the
contents of the error.
Note
Since the error code is added to "NAK" and is transmitted from the Q series C24 to the external
device when the "NAK" signal is turned on, take the corrective action described in the error code
table (see Section 11.2).
Since the error code added when "NAK" is transmitted is stored to the Q series C24 buffer
memory shown below, it can also be checked at the Q series C24.
Error code storage buffer memory address
CH1 side 25A
H
CH2 side 26A
H
• Communication error
signal "NAK" turned
on.
11.3.8 Communication error "C/N"
Symptom Cause Corrective action MC
Bidirectional
N
on
procedure
Pre-defined
• The Q series C24 cannot
be installed in the CPU.
• Change to a CPU to which the Q series C24
can be installed.
• PC No. designated local
station (FF), or a station
other than a station No.
set with the network
parameters.
• Change the PC No. to local station (FF), or a
station No. set with the network parameter
and restart data communications.
• Communication error
signal "C/N" turned
on.
• Routing parameters
between CPU with the Q
series C24 loaded and
communications
destination CPU are not
set.
• Check the routing parameters and set them
up to the communications destination CPU.