User`s manual

FX3U Series Programmable Controllers

User’s Manual - MODBUS Serial Communication Edition

7 MODBUS Standard Commands

7.11 Diagnostics (Command Code: 0x08)

7.11.8 Return bus communication error count (sub-command code: 0x0C)

Reads out the number of error messages detected on the line to the master.

1) Request message format (Master → Slave)

2) Response message format (Slave → Master)

(When completed normally)

*1. Refer to Chapter 6 for the relevant counts, count clear methods and precautions.

(When completed with an error)

*2. Exception and error codes are stored in special data registers and special auxiliary relays in the case

of error completion. Refer to Chapter 6 for storage location, confirmation methods, and other detailed

contents.

(L)

Data

(L)

Function code

Function

code

(08

Sub-function code

(000C

(0000

(H)

(L)

Data

(L)

Function code

Function

code

(08

Sub-function code

(000C

Bus communication

error count value

(0000

H to FFFFH) *

(H)

Data

Function code

Function

code

(88

Exception

code *