Mitsubishi Electric QJ71MB91 User Manual page 310

11
TROUBLESHOOTING
No. Symptom
The Automatic
7 communication error
status (X7/XF) turned on.
The CH common/CH1
8 error (X1B) or CH2 error
(X1C) turned on.
The MODBUS device
assignment parameter
9
setting existence (XA)
does not turn on.
11
- 4 11.1 Troubleshooting
Table11.2 Troubleshooting of errors indicated by X signals (Continued)
Check point
Check if the timer settings in the automatic
communication parameters are
appropriate.
Were the automatic communication
function and the MBRW or MBREQ
instruction used on the same channel?
Refer to "The ERR. LED turned on."
Is the slave function used?
Is the MODBUS device assignment
parameter setting completed?
Check if the MODBUS device assignment
parameter setting, error completed (X9) is
on.
Corrective action
• Check the processing time of the target
device.
• Check if, because of a small request
interval timer value, another request is
transmitted before receiving a response
from the target device.
• Check if, because of a small response
monitoring timer value, the timer has
timed out with an error before the target
device returns a response.
For the error, set a larger response
monitoring timer value.
• Check if the next request was sent
before completion of the processing of
the target device because of a small
broadcast delay value.
For the error, set a larger broadcast
delay value.
Set automatic communication parameters
and create a sequence program
appropriately so that each of the MBRW
and MBREQ instructions can be executed
in the right timing.
When the slave function is not used, the
MODBUS device assignment parameter
setting existence (XA) is off.
Set the MODBUS device assignment
parameters by GX Configurator-MB.
Or, set the MODBUS device assignment
parameters by a sequence program.
In the setting for the MODBUS device
assignment parameter starting method on
the intelligent function module switch,
select "OFF: Start with the default
parameters".
Refer to "MODBUS device assignment
parameter setting, error completed (X9)
turned on."
Reference
Section 7.2.1
Section 9.2.3
This section
(1)-2
-
Section 7.3
Section 9.1.2
Section 6.6
This section
(2)-4