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MELSEC-Q
11 TROUBLESHOOTING
11.3.10 Communication error "PRO."
Symptom Cause Corrective action
MC
Bidirectional
Non
procedure
Pre-defined
• Communication error
signal "PRO" turned
on.
• Communications were
performed with a control
procedure different from the
Q series C24 communication
protocol setting.
• Check the Q series C24 communication protocol
setting and the message from the external device
and match the settings, or correct the message and
restart data communications.
• Use the communication monitoring function to check
the message from the external device.
• Some of the data are
different from the control
procedure.
• Designated command does
not exist.
• The device No. designation
is not the character count
corresponding to the
command.
• The characters in the
message include a data
other than the "A to Z", "0 to
9", "
", and control data.
• Check and correct the external device message and
restart data communications.
• Use the communication monitoring function to check
the message from the external device.
Note
• Only the data "0 to 9" and "A to F" can be handled
as character area data during communications
using an MC protocol (ASCII mode). Therefore,
when transmitting a character string as data,
convert the ASCII code of each character string to
2-byte binary code.
Examples)
• Transmitting the character "G"
The ASCII code for the character "G" is 47
H and
is transmitted as the two bytes 34
H, 37H.
• Transmitting the character "A"
The ASCII code for "A" is 41
H and is transmitted
as the two bytes 34
H, 31H.
If the ASCII code 41H for the character
"A" is transmitted unchanged, the Q series
C24 ASCII-BIN conversion will convert it to
A
H
(10) and pass it to the programmable
controller CPU.
• A device No. outside the
designated range was
designated.
• When designating a device, check "Device setting"
of the parameters written to the CPU and correct it to
a device No. within the designated range and restart
data communications.
• A remote RUN/STOP
request was issued while
remote STOP was applied
from another module.
• Check if remote STOP is applied from another
module and restart data communications.
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