B&B Electronics GW-7472 - Manual - Manual (Page 40)

GW-7472 User Manual, Version 1.0, Dec 2010 --- 40
GW-7472 allows setting maximum 30 Modbus commands to get the register data of the Modbus
slaves. The unit of the input instance and output instance is BYTE. Therefore, no matter the
data format is Coil (1 bit) or WORD, all of the register data of the Modbus slaves will be
assigned to the instances of the Assembly Object by using BYTE format. While creating a
mapping table, the data in the same Modbus command will be put together and be mapping to
some section of the instance by using integral number of bytes. The input register data of the
first Modbus command defined by the Utility are mapping to the most front end of the input
instance. The input register data of the following Modbus command are mapping to the following
section of the input instance. The situation is the same at the mapping of the output instance.
The maximum data size of the input instance and output instance are 500 bytes respectively.
The following figure shows the general concept of the mapping information of the input instance
and output instance. For details about the input, output and status instances, please refer to the
“Appendix A (4. Assembly Object (04
hex
)) ”.