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CRC-16 Calculation Example:
crcsum# = &HFFFF&
crcshift# = &H0&
crcconst# = &HA001&
CLS
PRINT "***************************************************"
PRINT
PRINT "
CRC-16 calculator"
PRINT
PRINT "***************************************************"
PRINT "If entering data in hex, preceed the data with '&H'"
PRINT "
Example: 32decimal = 20hex = &H20"
PRINT "***************************************************"
PRINT
INPUT "Enter the number of bytes in the message: ", maxbyte
FOR bytenum = 1 TO maxbyte STEP 1
PRINT "Enter byte "; bytenum; ":":
INPUT byte&
byte& = byte& AND &HFF&
crcsum# = (crcsum# XOR byte&) AND &HFFFF&
FOR shift = 1 TO 8 STEP 1
crcshift# = (INT(crcsum# / 2)) AND &H7FFF&
IF crcsum# AND &H1& THEN
crcsum# = crcshift# XOR crcconst#
ELSE
crcsum# = crcshift#
END IF
NEXT shift
NEXT bytenum
lower& = crcsum# AND &HFF&
upper& = (INT(crcsum# / 256)) AND &HFF&
st
PRINT "Lower byte (1
nd
PRINT "Upper byte (2
GPD315 Modbus RTU Technical Manual TM 4325
) = ", HEX$(lower&)
) = ", HEX$(upper&)
Figure 4-1 CRC Calculation in Quick Basic
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