Modbus RTU Function Codes
The following Modbus RTU functions are supported by family drives:
| Function Code | Description |
|---|---|
|
03 |
Read holding registers (read n words) |
|
06 |
Preset single register (write 1 word) |
|
16 |
Preset multiple registers (write n words) |
Modbus RTU Function Code: 03
The function Code 03 (read n words) is the primary command to acquire drive’s parameters data. This function implemented on family drives supports the reading of more than one drive’s parameter at a time regardless of its length (one or more data words). The broadcast is not supported.
Function Code 03 format:
| Byte 0 | Byte 1 | Byte 2 | Byte 3 | Byte 4 | Byte 5 | Byte 6 | Byte 7 |
|---|---|---|---|---|---|---|---|
|
Slave Address |
Function |
Register Address HI |
Register Address LO |
# of Words HI |
# of Words LO |
CRC LO |
CRC HI |
|
xx |
03 |
xx |
xx |
00 |
xx |
xx |
xx |
Modbus RTU Function Code: 06
The function Code 06 (write 1 word) is used to set drive’s one word long parameters. This function implemented on family drives supports the writing of one drive’s parameter at a time. The broadcast is supported.
Function Code 06 format:
| Byte 0 | Byte 1 | Byte 2 | Byte 3 | Byte 4 | Byte 5 | Byte 6 | Byte 7 |
|---|---|---|---|---|---|---|---|
|
Slave Address |
Function |
Register Address HI |
Register Address LO |
Data HI |
Data LO |
CRC LO |
CRC HI |
|
xx |
06 |
xx |
xx |
xx |
xx |
xx |
xx |
Modbus RTU Function Code: 16
The function Code 16 (write n words) can set all drive’s parameters. This function implemented on family drives supports writing of more than one drive’s parameter at a time regardless of its length (one or more data words). The broadcast is supported.
Function Code 16 format:
| Byte 0 | Byte 1 | Byte 2 | Byte 3 | Byte 4 | Byte 5 | Byte 6 | Byte 7 | Byte 8 | Byte 9 | Byte 10 |
|---|---|---|---|---|---|---|---|---|---|---|
|
Slave Address |
Function |
Starting Address HI |
Starting Address LO |
# of Words HI |
# of Words LO |
Byte Count |
Data 0 HI |
Data 0 LO | Data 1 HI | Data 1 LO |
|
xx |
10 |
xx |
xx |
00 |
xx |
xx |
xx |
xx | xx | xx |
|
Byte n |
Byte n+1 |
Byte n+2 |
Byte n+3 |
|---|---|---|---|
|
Data n HI |
Data n LO |
CRC LO |
CRC HI |
|
xx |
xx |
xx |
xx |
Modbus RTU Function Code: 23
The function Code 23 (read/write n words) can set and get all drive’s parameters. This function implemented on family drives supports writing and reading of more than one drive’s parameter at a time regardless of its length (one or more data words). The broadcast is not supported.
Function Code 23 format:
| Byte | Byte 1 | Byte 2 | Byte 3 | Byte 4 | Byte 5 | Byte 6 | Byte 7 | Byte 8 | Byte 9 | Byte 10 | Byte 11 | Byte 12 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Slave Address |
Function |
Starting Read Address HI |
Starting Read Address LO |
# of Words Read HI |
# of Words Read LO |
Starting Write Address HI |
Starting Write Address LO |
# of Words Write HI | # of Words Write LO | # of Words Write Data Bytes | Write Data 0 HI | Write Data 0 LO |
|
xx |
17 |
xx |
xx |
00 |
xx |
xx |
xx |
00 | xx | xx | xx | xx |
| Byte n | Byte n+1 | Byte n+2 | Byte n+3 |
|---|---|---|---|
| Write Data n HI | Write Data n LO | CRC LO | CRC HI |
| xx | xx | xx | xx |
