Tonghui TH2840 Series - Page 186

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2 bytes.
e) Total number of bytes
It represents the total number of bytes written in this operation.
f) Data byte 1~data byte n
Write these data content to the instrument.
g) CRC high and CRC low
CRC 16-bit check, we use the look-up table method for CRC check.
 Example: The specific instruction and function setting relationship is detailed in the Appendix
Table ModeBus command function comparison table (Section 9.3.3);
Set the voltage range, set to Range 2 (ie 300V), the storage address of voltage range parameter in
the instrument is 0x0003, the instrument bus address is 8.
Then the command is:
Where, the countdown 3
rd
is corresponding to 20% index value of voltage, the type is char and
accounting for 1 byte.
The return information is as follows:
9.3.1.2 Reading the command
 Sending format
Instrument
address
Function
code
High
address
Low
address
High
registers
Low
registers
CRC
Low
CRC
High
 Return format
Instrument
address
Function
code
Total
number
of bytes
Data
byte 1
……
Data
byte n
CRC Low
CRC High
The function code is: 0x03
 Example: The specific instruction and function setting relationship is detailed in the Appendix
Table ModeBus command function comparison table (Section 9.3.3);
To read the test value of the voltage in the current mode, the storage address is 0x00A0, the
instrument number is 8.
Then the command is:
0x08
0x03
0x00
0xA0
0x00
0x02
0xC4
0xB0
The return information is as follows:
0x08
0x0
3
0x0
4
Data
byte 1
……
Data
byte 4
CRC
Low
CRC
High
0x08
0x10
0x00
0x03
0x00
0x01
0x01
0x02
C5
FD
0x08
0x10
0x00
0x03
0x00
0x01
0XF1
0x50