Communication Error "Nak; Communication Error "C/N - Mitsubishi Electric QJ71C24N User Manual

11 TROUBLESHOOTING

11.3.7 Communication error "NAK"

Symptom
• Communication error
signal "NAK" turned
on.

11.3.8 Communication error "C/N"

Symptom
• Communication error
signal "C/N" turned
on.
11 - 42
Cause
• 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.
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.
CH1 side
CH2 side
Cause
• The Q series C24 cannot
be installed in the CPU.
• PC No. designated local
station (FF), or a station
other than a station No.
set with the network
parameters.
• Routing parameters
between CPU with the Q
series C24 loaded and
communications
destination CPU are not
set.
Corrective action
• Take corrective action corresponding to the
contents of the error.
Error code storage buffer memory address
Corrective action
• Change to a CPU to which the Q series C24
can be installed.
• Change the PC No. to local station (FF), or a
station No. set with the network parameter
and restart data communications.
• Check the routing parameters and set them
up to the communications destination CPU.
MELSEC-Q
25A
H
26A
H
11 - 42