User`s manual

71
FX3U Series Programmable Controllers
User’s Manual - MODBUS Serial Communication Edition
7 MODBUS Standard Commands
7.12 Get Communications Event Counter (Command Code:
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
7.12 Get Communications Event Counter (Command Code: 0x0B)
Acquires the number of messages whose requested actions (read/write, diagnostics, etc.) have been
normally completed.
Note
Only normally completed messages are counted.
1) Request message format (Master → Slave)
2) Response message format (Slave → Master)
(When completed normally)
*1. Since the FX-Series MODBUS Communication ADP does not support any program commands,
0000H is stored.
*2. The count is stopped if it has reached FFFFH.
Reset the counter by either of the following methods when restarting the count.
Clearing the counter and diagnostic register (Refer to Subsection 7.11.6).
Restart communications option (Refer to Subsection 7.11.2).
Power OFF → ON, or the PLC state is changed from STOP → RUN.
Note
The communications event counter counts only when the processing (read/write, diagnostics, etc.) has
completed normally.
The communications event counter does not count in the case of the following:
The processing has completed with an error.
• When receiving a request message containing a function code that the FX-Series MODBUS
Communication ADP does not support
• When receiving the Get communications event counter (FC: 11)
(When completed with an error)
*3. 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.
Function code
Function
code
(0B
H)
(L)
Data
(L)
Function code
Function
code
(0B
H)
Program command status
(0000
H) *
1
Communications
event count value
(0000
H to FFFFH) *
2
(H)
(H)
Data
Function code
Function
code
(8B
H)
Exception
code *
3