Emerson Commander SX - Page 136

136
ADVANCED USER GUIDE
Commander SX
IP66/Nema 4X variable speed drive
OPERATION WITH MODBUS RTU
CONTROL TECHNIQUES
3854 en - 03.2008 / b
• Function code 16: Write multiple
Writes a contiguous array of registers. The slave imposes an
upper limit on the number of registers which can be written. If
the limit is exceeded, the slave does not respond.
Note: 12 parameters maximum can be written.
Frame sent by the Master:
Where n = 7 + number of bytes to be written.
Frame returned by the slave:
• Function code 23: Read/write
Writes and reads two contiguous arrays of registers. The
slave imposes an upper limit on the number of registers which
can be written. If the limit is exceeded, the slave does not
respond.
Note: 99 parameters maximum can be read and 10
parameters maximum can be written.
Frame sent by the Master:
Where n = 11 + number of bytes to be written.
Frame returned by the slave:
Where n = 3 + number of bytes to be read.
Bytes Description
0 Slave address (1 to 247)
1 Function code 0x10
2 Start word address MS byte
3 Start word address LS byte
4 Number of words to be written MS byte
5 Number of words to be written LS byte
6 Number of bytes to be written
7 Word 0 to be written MS byte
8 Word 0 to be written LS byte
9 Word 1 to be written MS byte
10 Word 1 to be written LS byte
... …
n CRC LS byte
n + 1 CRC MS byte
Bytes Description
0 Slave address (1 to 247)
1 Function code 0x10
2 Start word address MS byte
3 Start word address LS byte
4 Number of words written MS byte
5 Number of words written LS byte
6 CRC LS byte
7 CRC MS byte
Address of 1st word
Number of words
CRC
No. of bytes
Word number 0
Word number 1
…
Slave no.
Command (10h)
1 hexadecimal
byte
1 hexadecimal
byte
2 hexadecimal
bytes
2 hexadecimal
bytes
Slave no.
Address of 1st word
Number of words
CRC
1 hexadecimal
byte
2 hexadecimal
bytes
Command (10h)
Bytes Description
0 Slave address (1 to 247)
1 Function code 0x17
2 Start word to be read address MS byte
3 Start word to be read address LS byte
4 Number of words to be read MS byte
5 Number of words to be read LS byte
6 Start word to be written address MS byte
7 Start word to be written address LS byte
8 Number of words to be written MS byte
9 Number of words to be written LS byte
10 Number of bytes to be written
11 Word 0 MS byte
12 Word 0 LS byte
13 Word 1 MS byte
14 Word 1 LS byte
... …
n CRC LS byte
n + 1 CRC MS byte
Bytes Description
0 Slave address (1 to 247)
1 Function code 0x17
2 Number of bytes to be read
3 Word 0 MS byte
4 Word 0 LS byte
5 Word 1 MS byte
6 Word 1 LS byte
... …
n CRC LS byte
n + 1 CRC MS byte