User`s manual

59
FX3U Series Programmable Controllers
User’s Manual - MODBUS Serial Communication Edition
7 MODBUS Standard Commands
7.11 Diagnostics (Command Code: 0x08)
1
Outline
2
Specifications
3
System Configuration
4
Wiring
5
Communication Setup
6
Related Devices and Comm. Status
7
MODBUS Standard Commands
8
Master Specification
9
Slave Specification
10
Creating Programs
7.11.3 Return diagnostic register (sub-command code: 0x02)
Reads out the diagnostic register of the remote node to the master.
1) Request message format (Master → Slave)
2) Response message format (Slave → Master)
(When completed normally)
*1. When using 3rd party products. The high byte (H) does not equal 00H. For further information on the
specifications for the slave refer to Chapter 9.
(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
H)
Sub-function code
Sub-function code
(0002
H)
(0000
H)
(H) (H)
(L)
Data
(L)
Function code
Function
code
(08
H)
Sub-function code
Sub-function code
(0002
H)
Diagnostic register
value
(H)
(H)
00 H
M8060-M8067
(When using CH1 for MODBUS communication)
M8060-M8062,M8438, M8064-M8067
(When using CH2 for MODBUS communication)
(FX 3U )
*1
Data
Function code
Function
code
(88H)
Exception
code*
2