Xantrex Technology Freedom SW Series manual Modbus Byte Order

Configuration

All of the RS 485 and Modbus settings for the Conext ComBox can be changed as necessary. The default value for the Modbus TCP Port is 502 and the Server Modbus Address is 201.

Select Listening in Modbus TCP Enabled to enable Modbus communication.

Note:

When writing a character string using function code 0x10 (Write Multiple

Registers), the NUL terminator MUST be written or the string will not be stored.

When writing 32-bit modbus registers, both 16-bit registers which make up the 32-bit value must be written in order to store the data.

Modbus Byte Order

You can configure the Conext ComBox to change the Modbus byte and word

ordering for packed ASCII strings, and 32-bit values. There are two settings for Modbus Byte Order:

	1.	Least Significant byte/word first (LSB First)
	2.	Most Significant byte/word first (MSB First)
	Select the appropriate setting for your Modbus network.
	The following are examples of how the settings operate.
Packed String	When sending the text string "CONEXT" over Modbus:
Example:	1.	Least Significant byte:

		O	C	E	N	T	X
	2.	Most Significant byte:
		C	O	N	E	X	T
32-bit Word	When sending the value 0x12345678 over modbus:
Example:	1.	Least Significant word:

5 6 7 8 1 2 3 4

2. Most Significant word:

1 2 3 4 5 6 7 8

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