Flachmann und Heggelbacher Docklight V2.2, User Manual

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Docklight V2.2 User Manual 07/2016 Copyright 2016 Flachmann und Heggelbacher GbR
Reference
@ -4 By default Docklight places the checksum result at the end of the
sequence data, unless you have specified "A" for ASCII result. In this
case, the results is stored one character before the end, so there is
still space for a "end of line" character, typically a CR as in MODBUS
ASCII.
# comment You can type in a comment about this checksum specification
Remarks
startPos , len and targetPos support negative values, too, as a way to specify positions
relative to the end of the sequence and not relative to the start of the sequence.
Examples:
startPos is -4 : start calculating at the 4th character from the end.
len is -1 : use everything until the end of the sequence.
targetPos is -1 : first (and only) byte of the result is stored at the last sequence
character position.
targetPos is -2 : result is stored starting at the 2nd character from the end.
targetPos is -3 : result is stored starting at the 3rd character from the end.
Examples
# (off, no checksum)
MOD256 # simple one byte sum on all but the last character"
CRC-MODBUS L # MODBUS RTU checksum. Lower Byte first ('Little
Endian')
CRC-MODBUS A @ -5 # MODBUS ASCII checksum returned as text
(1,3) CRC-16 @ 10 # CRC-16 checksum over the first 3 bytes.
(2, -5) CRC:8,07,00,00,No,Yes # CRC with custom, non-standard
spec.