Omron V680 Series User Manual

Section 7 Modbus Communications Protocol
Section 7
Host Communications Specifications
159
RFID System
User's Manual
(Modbus TCP)
Message Formats
The host device communications protocol that is used by the V680S is based on Modbus TCP.
The command message that the host device sends to the Reader/Writer is called a query. The
response message that the Reader/Writer returns is called the response. The communications formats
for queries and responses are given below.
 Query format
Transaction Identifier
You can set any desired value. The transaction identifier in the response from the Reader/Writer will be
a copy of the value that is specified here.
Protocol Identifier
This field is always 0000 hex.
Field Length
Specify the number of bytes inclusively from the unit identifier through the end of the data.
Byte 4 will always be 00 hex.
Unit Identifier
This field is always FF hex.
Function code
Specify the function code of the function for the Reader/Writer to execute.
The applicable function codes are listed below.
Data
Send the data for the function code.
The format of the data depends on the function code.
Of the data types that are supported by Modbus communications, the Reader/Writer supports the
following data type.
Function code Function
03 hex Read Holding Register
10 hex Write Holding Register
Data name Description
Holding register Read/write 16-bit data
Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8 Byte 9 ··· Byte n
Transaction
identifier
Protocol identifier Field length
Unit
identifier
Function
code
Data
X X Always 0000 hex
Always
00 hex
No. of
bytes
Always
FF hex
03 or 10 hex
Range specified with the field length
X: Any value

Omron V680 Series Specifications

General

Brand	Omron
Model	V680 Series
Category	Other
Language	English