Mitsubishi Electric MELSEC-Q/L Programming Manual page 458

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Table of Contents

■8-bit conversion mode (when SM772 is ON)

CRC operation is performed for the lower 8 bits (lower byte) of the data in the device specified by (S). The operation result is

stored using the two points from the device specified by (D): lower 8 bits (byte units) are stored in the device specified by (D)

and upper 8 bits (byte units) are stored in the device specified by (D)+1. In 8-bit conversion mode, the 6 bytes at the shaded

positions in the following figure are the operation target. Here, the CRC value is "BDA1H" and accordingly "A1H" is stored in

the device specified by (D) and "BDH" is stored in the device specified by (D)+1.

Operation error

• In any of the following cases, an operation error occurs, the error flag (SM0) turns ON, and an error code is stored into SD0.

Error details

A digit other than 4 is specified in the digit-specified bit device in (S), (D).

The value in the device specified by the instruction exceeds the setting

(S)+n-1, (D)+1 is out of the device range.

Program example

• The sample program calculates the CRC value of six points of data in the devices starting from D0 and stores the result in

the devices specified by D100.

[Ladder Mode]

7 APPLICATION INSTRUCTIONS

7.5 Data Processing Instructions

Upper bits Lower bits