Reference Number; Word Count; Example; Modbus Register Mapping - Vertiv HPL Operation Manual

Table 3.1 Function Code Descriptions (continued)
CODE FUNCTION
Read Input
04
Registers
Write Single
05
Coil
Write Single
06
Register
Write
15 Multiple
Coils
Write
16 Multiple
Registers

4.2.3 Reference number

The reference number field provides the slave BMS with the offset register value for the given function code designated
register start point. This field value will be added to the function code starting address for the actual register value.

4.2.4 Word Count

The word count field represents the number of 16-bit registers requested to be read or written.

4.2.5 Example

A Modbus client requests a BMS at the IP address of 126.4.91.4 to read 125 Input registers starting at register 36001.
• Device IP Address: 126.4.91.4
• Function Code: 04
• Reference Number: 6000
• Word Count: 125

4.3 Modbus Register Mapping

4.3.1 Common Data

DATA DESCRIPTION
Common Data
BMS Protocol
Major/Minor
Enclosure Position
10
DESCRIPTION
Read from 1 to 125 contiguous input registers. Register data in the response message are packed as two bytes per register, with
the first byte containing the high order bits. Starting Register: 30001 (39999)
Write a single output to either On (1) or Off (0) of the status of a mapped coil register.
Write a two-byte value to a single holding register.
Used to force each coil, in a sequence of coils, to either On (1) or Off (0).
Write values to a block of registers ranging from 1 to 120.
INPUT
REFERENCE #
REGISTER
30001 0 (0x0h)
30002 1 (0x1h)
# OF
SCALE UNITS NOTES
REG
Major –
upper 8 bits
1
Minor –
lower 8 bits
1 Range: 1 - 32
Vertiv™ | Vertiv™ HPL Lithium-Ion Energy Storage System Operation Guide