9
4. Modbus communication
4.1 Overview
●
Function that supports Modbus protocol. Modbus protocol specifications have been globally
disclosed; Modbus protocol is one of the most common types of communication protocol.
●
Modbus protocol does not support messages autonomously output by the IJ Printer such as
status or printing contents.
4.2 Transmission procedure
No. Name Size
Setting
range
Description
1 Transaction
identifier
2 bytes 0x0000 to
0xFFFF
The IJ Printer returns the transaction
identifier received from external unit as it is.
You should use the identifier to manage
messages for external unit.
2 Protocol identifier
2 bytes
0x0000 Sets protocol identifier. Set protocol identifier
to 0x0000. The IJ Printer returns the protocol
identifier received from external unit as it is.
3 Data length
2 bytes 0x0000 to
0x00FF
Sets number of bytes for request data and
response data.
4 Data
3 to 255
bytes
-
Because message format differs according
to the function code specified, data size is
variable refer to 4.3 Message format for
details.
4.3 Message format
(1) Function code
The IJ Printer supports the function code given in the following table.
Function code
No.
Function
code
Function
1
0x10
Write Multiple Registers
2
0x06
Write Single Register
3
0x03
Read Holding Registers
4
0x04
Read Input Registers
Transaction
identifier
External unit
IJ Printer
Protocol
identifier
Data length
Data
Transaction
identifier
Protocol
identifier
Data length
Data
Request message
configuration
Response message
configuration
