Crc Operation - Mitsubishi Electric MELSEC-Q/L Programming Manual

CRC operation

CRC(P)
High
Basic Process
Redundant
performance
• QnUDVCPU, LCPU: The serial number (first five digits) is "16112" or later.
CRC
CRCP
(S): Start number of the devices where the target data of CRC value generation is stored (BIN 16 bits)
(D): Number of the device where the CRC value generated is stored (BIN 16 bits)
n: Number of 8-bit data blocks for which the CRC value is to be determined or the number for the device where the number of 8-bit data blocks is stored
(setting range: 1 to 256) (BIN 16 bits)
Setting Internal device
data
Bit Word
 
(S)
 
(D)
 
n
Processing details
• Generates the CRC value of n points of 8-bit data (byte units) starting from the device specified by (S) and stores it in the
device specified by (D). "X
instructions support two modes, 16-bit conversion mode and 8-bit conversion mode, used for calculation of the CRC value.
The two conversion modes can be selected by SM772 ON/OFF. The operation in each conversion mode is described
below.
■16-bit conversion mode (when SM772 is OFF)
CRC operation is performed for the upper 8 bits (byte units) and lower 8 bits (byte units) in the device specified by (S). The
operation result is stored in the 16 bits of one point of the device specified by (D). The CRC value when n = 6 is shown below.
In 16-bit conversion mode, the 6 bytes at the shaded positions in the following figure are the operation target. Here, the CRC
value is "A57BH" and accordingly "A57BH" is stored in the device specified by (D).
Hexadecimal
Device Decimal
Upper bits Lower bits
D0 24932 61
H
D1 4219 10
H
D2 -1333 FA
H
D3 -1 FF
H
D4 32761 7F
H
D5 10000 27
H
Ver. Ver.
LCPU
Universal
Command
Command
R, ZR J\
Bit
 
 
 
16 15 2
+X +X +1" is used as the generator polynomial to generate the CRC value. These
64
H
7B
H
CB
H
FF
H
F9
H
10
H
CRC S D
CRCP S D
U\G Zn
Word
  
  
  
7 APPLICATION INSTRUCTIONS
7.5 Data Processing Instructions
n
n
Constant Others
K, H
 
 
 
455
7