ET-7000/PET-7000 AIO Series User Manual, version 1.0.1 beta3 Page: 91
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4.2.1. Address
The first byte of information in the message structure of Modbus is the receiver’s address.
The valid addresses are in the range of 0 to 247. Addresses from 1 to 247 are given to
individual Modbus devices and 0 is used for broadcast.
Reference
Description
0xxxx
Read/Write Discrete Outputs or Coils. A 0x reference
address is used to device output 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 reference register contains a 16-bit
number 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 dada (binary or decimal),
or to send the data from the CPU to an output channel.