IDEC microsmart pentra, Programming Manual

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25: U
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NSTRUCTIONS
25-18 FT1A S
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ANUAL
FT9Y-B1382
Conversion Type
The BCC calculation result can be converted or not according to the designated conversion type as described below:
Example: BCC calculation result is 0041h.
(1) Binary to ASCII conversion
(2) No conversion
BCC Digits (Bytes)
The quantity of digits (bytes) of the BCC code can be selected from 1 or 2.
Example:
Comparing BCC Codes
The SmartAxis compares the BCC calculation result with the BCC code in the received incoming data to check for any error in the incoming
communication due to external noises or other causes. If a disparity is found in the comparison, an error code is stored in the data register
designated as receive status in the RXD instruction. For user communication error code, see page 26-32.
Example 1: BCC is calculated for the first byte through the sixth byte using the XOR format, converted in binary to ASCII, and
compared with the BCC code appended to the seventh and eighth bytes of the incoming data.
Note: On WindLDR, Modbus ASCII is defaulted to
binary to ASCII conversion.
Note: On WindLDR, Modbus RTU is defaulted to no
conversion.
Note: On WindLDR, Modbus ASCII and Modbus RTU
are defaulted to 2 digits.
0041h
Binary to ASCII conversion
“4”
(34h)
“1”
(31h)
2 digits
0041h
No conversion
NUL
(00h)
“A”
(41h)
2 digits
(1) BCC digits = 2
“4”
(34h)
“1”
(31h)
“4”
(34h)
“1”
(31h)
(2) BCC digits = 1
“4”
(34h)
“1”
(31h)
“1”
(31h)
Lower digit
“1”
(31h)
“2”
(32h)
BCC Calculation Range
“3”
(33h)
“4”
(34h)
Incoming Data
“5”
(35h)
“6”
(36h)
“0”
(30h)
“7”
(37h)
BCC
31h  32h  33h  34h  35h  36h = 07h
“0”
(30h)
“7”
(37h)
BCC Calculation Result
Binary to ASCII Conversion
Comparison result is true to indicate that data
is received correctly.