Omron V780 Series, User Manual

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7 - 5
7 Modbus/TCP Communications
UHF RFID System V780-series Reader/Writer User’s Manual (Z389)
7-
2 Messag
e Fo
rmat
s
7
7-2
-1 Comma
nd For
m
at
7-2 Message Formats
This value is used to identify the message sent by the host device.
The transaction identifier in the response from the Reader/Writer will be a copy of the value that is
specified here.
This field is always 0000 hex.
Specify the number of bytes inclusively from the unit identifier through the end of the data.
If the function code is FC03 or FC16, the maximum field length is 250 bytes.
If the function code is FC100, the maximum field length is 4,346 bytes.
This field is always FF hex.
The function code indicates the command to request execution from the Reader/Writer.
7-2-1 Command Format
Byte-0 Byte-1 Byte-2 Byte-3 Byte-4 Byte-5 Byte-6 Byte-7 Byte-8 Byte-9 … Byte-n
Transaction iden-
tifier
Protocol identifier Field length
Unit
identifier
Func-
tion
code
Data
XXXX hex Always 0000 hex. XXXX hex
Always
FF hex.
03 hex,
10 hex,
or 64
hex
XX...XX hex
X: Any value, n: 4,351 max.
Transaction Identifier
Protocol Identifier
Field Length
Unit Identifier
Function Code
Function code Function Remarks
FC03 (03 hex) Read Multiple Registers Modbus/TCP Class 0 compliant
FC16 (10 hex) Write Multiple Registers
FC100 (64 hex) Reader/Writer command
This function code is used for commands
with a unique manufacturer definition that
gives priority to the performance of commu-
nications with the host device.
Range included in the field length.
Command frame length