3. Instruction Set
The error checksum LRC CHK (0, 1) can be calculated by LRC instruction (8-bit mode, M1161 =
ON).
LRC checksum: 01 H + 03 H + 07 H + 08 H + 00 H + 06 H = 19 H. Operate 2’s complement on 19H
and the result is E7H. Store ‘E’(45 H) in the low byte of D113 and ‘7’ (37 H) in the low byte of D114.
Remarks:
ASCII mode communication data:
Start word = ‘: ’ (3AH)
Communication:
8-bit address consists of 2 ASCll codes
Function code:
8-bit function consists of 2 ASCll codes
…….
DATA 0
n × 8-bit data consists of 2n ASCll
codes
LRC checksum:
8-bit checksum consists of 2 ASCll codes
End word:
END Hi = CR (0DH), END Lo = LF(0AH)
LRC checksum: Operate 2’s complement on the summed up value from communication address
to the end of data, i.e. 01 H + 03 H + 21 H + 02 H + 00 H + 02 H = 29 H, the operation result of 29H
is D7H.