Fm210_01b_oi_e.docx / Nov-20
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The unit will answer if the request is correct:
ADR FCT CB DATA CRCL CRCH
ADR = MB address (Parameter)
FCT = function (Hex 03)
CB = number of bytes, here 4 bytes
DATA = data, 4 bytes (32 Bit)
CRCx = checksum CRC16
Designation:
ADR
FCT
CB
DATA
CRCL CRCH
Hexadecimal:
07
03
04
00 00 0F A0
99
BB
Binary:
0000
0111
0000
0011
0000
0100
1001
1001
1011
1011
The data above corresponds to a read out of the parameter Ref Speed High of 4000.
-The function Reading Holding Registers supports 2 Word (32-bit) accesses to the direct parameter
addresses (0x0, 0x4, 0x8, 0xC ..)
- The function Reading Holding Register also supports more than 2 Word accesses to the direct
parameter addresses (0x0, 0x4, 0x8, 0xC ..) for area readout
Modbus Write
To write data to the unit, the following string must be sent:
ADR FCT REH REL DAH DAL CRCL
CRCH
ADR = MB address (parameter)
FCT = function (hex 06)
REH = register address, high byte
REL = register address, low byte
DAH = data high byte
DAL = data low byte
CRCL = checksum CRC16, low byte
CRCH = checksum CRC16, high byte
If for example the unit shall be written with the parameter Ref Speed High (Modbus ST = 00 0E, 000C
(hex), Modbus DA = 00 01, 00 01), then the detailed request string for the High Word Register is:
Designation:
ADR
FCT
REH
REL
DAH
DAL
CRCL CRCH
Hexadecimal:
07
06
00
0E
00
01
29
AF
Binary:
0000
0111
0000
0011
0000
0000
0000
1110
0000
0000
0000
0001
0010
1001
1010
1111
