13: T
ROUBLESHOOTING
FC5A M
ICRO
S
MART
U
SER
’
S
M
ANUAL
FC9Y-B1268
13-25
Troubleshooting Diagram 18
Confirm slave settings again.
Make sure that the slave is compatible
with the function code.
Make sure that the slave number and
communication settings are
correct.
Are communication
parameters equal at master and
slave?
Modbus master communication
does not work.
Are error data stored
in D8069 to D8099? (Note)
YES
NO
Is request
execution IR designated and
turned on?
YES
NO
NO
Confirm communication settings using
WindLDR (see
page 12-4 (Basic Vol.)).
Confirm the slave number (high-order
byte) and error code (low-order byte)
(see page 12-14).
Make sure that slave address settings are
correct.
Turn on the request execution internal
relay.
YES
Is it clear which
request has an error?
NO
See the request table to find which
request has an error and what error
occurred (see page 12-4).
YES
01h (function error)?
NO
02h (access destination error)?
NO
YES
03h (device
quantity error, 1-bit write
data error)?
NO
YES
16h (timeout error)?
NO
YES
Make sure of the valid slave address
range and master settings.
YES
Data size and actual data may not
match. Make sure that slave settings
and hardware are correct (without
noise and failure).
Note:
Error data are stored in D8069 to D8099 when Modbus master is used with port 2. For port 3 through port 7, data registers
in which error data are stored are specified in the Function Area Settings.
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