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BCC (Block Check Code)
A BCC for the transmission data is automatically calculated and appended to the transmission data at an arbitrary
position and transmitted.
This can be configured only when TXD or Inching is selected as Type on the Command Settings dialog box, and
BCC is selected under Type on the Data Settings dialog box.
Calculation Start Position
■
Specify the position of transmission data at which BCC calculation starts (1 to 15). The position is counted backwards,
with the first position of the transmission data taken as 1.
Calculation Start Position:
Transmission data:
(02h)
Calculation End Position
■
Specify the position of transmission data at which BCC calculation ends (0 to 15). The position is counted forwards,
with the data position before the BCC taken as 0.
Transmission data:
(02h)
Calculation End Position:
■
Calculation Type
Select the method to calculate the data between the Calculation Start Position and Calculation End Position.
XOR:
Calculates the data with exclusive logical add.
ADD:
Calculates the data using addition.
ADD (2's Complement): Calculates the data using addition, inverts the bit and adds one.
Modbus ASCII (LCR):
Calculation is performed according to the following procedure. Conversion Type:
Hexadecimal to ASCII, Number of bytes: 2
1. Convert the ASCII characters between Calculation Start Position and Calculation End
2. Calculate the sum of the data obtained in step 1.
3. Invert the bit of the result of step 2 and add one. (2's complement)
4. Convert the lower one byte data of the result of step 3 into ASCII characters.
(1)
(2)
(3)
(4)
STX
1
2
3
(31h)
(32h)
(33h)
(34h)
STX
1
2
3
(31h)
(32h)
(33h)
(34h)
(5)
(4)
(3)
(2)
Position into 1-byte hexadecimal data for each set of two characters.
Example: 37h, 35h→75h
Example: 75h→37h, 35h
WindO/I-NV4 User's Manual
(5)
(6)
4
5
BCC
CR
(35h)
(0Dh)
4
5
BCC
CR
(35h)
(0Dh)
(1)
(0)
5 User Communication
3
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