GE Industrial Solutions WattStation Pedestal EVSE Charger MODBUS Register Mapping Guide - Manual (Page 12)

WattStation TM EV Charger MODBUS Register Guide
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• MODBUS FC 16 Request (note N = quantity of registers to write to)
Field Length (bytes) Value (hex)
Function Code 1 0x10
Starting Address 2 0x0000 to 0xFFFF
Number of Registers 2 0x0001 to 0x7B (1 to 123)
Byte Count 1 2 × N
Registers Value N × 2 Value
Table – 3.8
The Normal MODBUS function code 16 (0x10) Response PDU specifies the starting register address
and the number of registers to be written.
• MODBUS FC 16 Response
Field Length (bytes) Value (hex)
Function Code 1 0x10
Starting Address 2 0x0000 to 0xFFFF
Quantity of Registers 2 0x0000 to 0x7B (1 to 123)
Table – 3.9
3.3.5
Function Code 23 (0x17): Read and Write Holding Registers
Function code 23 (0x17) performs a combination of one read operation and one write operation in a
single MODBUS transaction. The write operation is performed before the read.
The MODBUS Function code 23 (0x17) Request PDU specifies the read starting register address, the
number of registers to be read, the write starting register address, the number of registers to be
written, the write data length, and the write data values. In the PDU Registers are addressed starting
at zero. Therefore registers numbered 1-16 are addressed as 0-15.
• MODBUS FC 23 Request (note N = Quantity of registers to Write)
Field Length (bytes) Value (hex)
Function Code 1 0x17
Read Starting Address 1 0x0000 to 0xFFFF
Number of Registers to Read 2 0x0001 to 0x7D (1 to 125)
Write Starting Address 2 0x0000 to 0xFFFF
Number of Registers to Write 2 0x0001 to 0x79 (1 to 121)
Write Byte Count 1 2 × N
Write Registers Value N × 2 Value
Table – 3.10