Azbil C7G User Manual

7-5
Chapter 7. Modbus RTU Communication Functions
The table below shows the processing related to illegal data addresses.
Start data
address
Second and later
data addresses
Exception code Message processing
Correct All correct Exception code for
illegal data address is
not added.
For a read command, all the data is read.
For a write command, all the data is written.
Correct Incorrect address is
included.
For a read command,
no illegal data address
exception code is
added.
For a write command,
the illegal data address
exception code is
added.
For a read command, data is read for the correct
addresses, and the values of incorrect addresses
are read as 0.
For a write command, data is written for correct
addresses and is not written for incorrect
addresses.
Incorrect All correct Exception code for
illegal data address is
added.
For a read command, data is not read.
For a write command, data is written for correct
addresses and is not written for incorrect
addresses.
Incorrect Incorrect address is
included.
If the version of the MAIN block firmware is earlier than 6.x.x (where x stands for
any number), the processing related to illegal data addresses is as shown in the table
below.
Start data
address
Second and later
data addresses
Exception code Message processing
Correct All correct Exception code for illegal
data address is not added.
For a read command, all the data is read.
For a write command, all the data is written.
Correct Incorrect address is
included.
Exception code for illegal
data address is added.
For a read command, data is not read.
For a write command, data is written for
correct addresses and is not written for
incorrect addresses.
Incorrect Incorrect address is
included.
Incorrect All correct

Amount of data
The amount of data that can be read or written using a 1-frame message is shown
below.
Command type
(Function code)
Number of data items
RAM EEPROM
Multiple data read (03) 1 to 32 1 to 32
Multiple data write (10) 1 to 32 1 to 32
1 data write (06) 1 1
Note
• For details on the specifications for Modbus communication, refer to the
following.
Modicon Modbus Protocol Reference Guide (PI-MBUS-300 Rev. J) by
MODICON, Inc.
• Open MODBUS/TCP Specification (Release 1.0) by Andy Swales (Schneider
Electric)

Azbil C7G Specifications

General

Brand	Azbil
Model	C7G
Category	Controller
Language	English