Troubleshooting diagram 18 – IDEC MicroSmart Pentra User Manual

Page 151

ERVER

CPU M

ODULE

SER

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ANUAL

FC9Y-B1278

13-25

13: T

ROUBLESHOOTING

Troubleshooting Diagram 18

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)

Is request execution

IR designated and

turned on?

Confirm communication settings using
WindLDR. See “Programming Modbus
Master Using WindLDR” of the basic
volume (page 12-4).

Confirm the slave number (high-order
byte) and error code (low-order byte).
See “Communication Error Data of Each
Slave” of the basic volume (page 12-4).

Make sure that slave address settings are
correct.

Turn on the request execution internal
relay.

Is it clear which request

has an error?

See the request table to find which request
has an error and what error occurred. See
“Communication Error Data of Each
Request” of the basic volume (page 12-4).

01h (function error)?

02h (access destination error)?

03h (device quantity error,

1-bit write data error)?

16h (timeout error)?

Make sure of the valid slave address
range and master settings.

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.

Confirm slave settings again.

YES