Supported Modbus features

Your meter supports specific Modbus data classes, data formats, function codes, and commands.

Modbus data classes

Class	Description
Coils	Digital bits that can be read and written to
Input status	Digital bits that can be read
Input registers	16-bit integers that can be read
Holding registers	16-bit integers that can be read and written to

Modbus data formats

Format	Type	# of Modbus registers used
Unsigned 16-bit	Integer	1
Signed 16-bit	Integer	1
Unsigned 32-bit	Integer	2
Signed 32-bit	Integer	2
Unsigned 32B-M10K	Integer	2
Signed 32B-M10K	Integer	2
IEEE float1	Floating point	2
Packed Boolean for inputs	Integer	1
Packed Boolean for coils	Integer	1
Unsigned 16-bit read/write	Integer	1
Signed 64 bit	Integer	4

¹ A device acting as a Modbus client supports two versions of IEEE float with different word orders: high/low = Big Endian, low/high = Little Endian.

16-bit data (one word) is transmitted with most-significant byte first and least-significant byte second.

32-bit data (two words) is transmitted with the most-significant word first and the least-significant word second.

Modbus function codes

Function	Description	Client / Server
1	Read coil status	Client and server
2	Read input status	Client and server
3	Read holding registers	Client and server
4	Read input registers	Client
5	Write to a coil	Client
6	Write to a holding register	Client and server
15	Write to multiple coils	Client
16	Write to multiple holding registers	Client and server
17	Report slave ID (serial only)	Client and server
43 (sub code 14)	Read device identification	Client and server
100	Read scattered holding registers	Client and server

Modbus commands

A Modbus client command to unit ID 0 is broadcast (sent to) all Modbus server devices. The only supported broadcast command is preset multiple registers.

For serial Modbus networks with only one server device, the client can send commands using the single connection, one-to-one address of unit ID 248, regardless of the server device’s actual unit ID.