Data Field - ICP DAS USA PET-AR400 User Manual

A.4. 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 ==> 0x0A, 0x0B. The data for 32-bit registers is
transmitted as two 16-bit registers, and is low-word first. For example: 0x0A0B0C0D ==> 0x0C,
0x0D, 0x0A, 0x0B. The data field of messages sent between a master and a slave 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)
0xxxx
1xxxx
3xxxx
4xxxx
PET-AR400 User Manual
Description
Read/Write Discrete Outputs or Coils.
A 0x reference address is used to output device data to a digital output
channel
Read Discrete Inputs.
The ON/OFF status of a 1x reference address is controlled by the
corresponding digital input channel.
Read Input Registers.
A 3x reference register contains a 16-bit number received from an
external source, e.g. an analog signal.
Read/Write Output or Holding Registers.
A 4x register is used to store 16bits of numerical data (binary or
decimal), or to send the data from the CPU to an output channel.
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