ET-2200 Series Ethernet I/O Modules
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Data Field
Data is transmitted in 8-, 16- and 32-bit format. The data for 16-bit registers is transmitted in high-
byte first format. For example: 0x0A0B will be transmittd as 0x0A, 0x0B. The data for 32-bit registers
is transmitted as two 16-bit registers, and is low-word first. For example: 0x0A0B0C0D will be
transmitted as 0x0C, 0x0D, 0x0A, 0x0B.
The data field for messages sent between a master device and a slave device contains additional
information about the action to be taken by the master, or any information requested by the slave.
If the master does not require this information, the data field can be empty.
Reference
(Address)
Description
0xxxx
Read/Write Discrete Outputs or Coils.
An 0x reference address is used to output device data to a Digital Output channel.
1xxxx
Read Discrete Inputs.
The ON/OFF status of a 1x reference address is controlled by the corresponding
Digital Input channel.
3xxxx
Read Input Registers.
A 3x reference register contains a 16-bit value received from an external source,
e.g. an analog signal.
4xxxx
Read/Write Output or Holding Registers.
A 4x register is used to store 16 bits of numerical data (binary or decimal), or to
send data from the CPU to an output channel.
Note:
For more details regarding the address mapping, refer to
(AIO) “Modbus Register Table”.
