Mitsubishi Electronics FX3G User Manual

FX

3S

/FX

3G

/FX

3GC

/FX

3U

/FX

3UC

 Series

Programming Manual - Basic & Applied Instruction Edition

24 Others – FNC181 to FNC189

This CRC instruction calculates the CRC (cyclic redundancy check) value which is an error check method used in
communication.
In addition to CRC value, there are other error check methods such as parity check and sum check. For obtaining the
horizontal parity value and sum check value, CCD (FNC 84) instruction is available.
For the generation of CRC value (CRC-16), the CRC instruction uses “X

16

 + X

15

 + X

2

 + 1” as a polynomial and uses

"FFFFH" as a default value.

→ For CCD instruction (check code), refer to Section 16.5.

S: Make sure to specify four digits (K4

) when specifying the digits of a bit device.

CRC value is generated for “n” 8-bit data (unit: byte) starting from a device specified in 

, and stored to 

.

The 8-bit conversion mode and 16-bit conversion mode are available in this instruction, and the mode can be switched
by turning ON or OFF M8161. For the operation in each mode, refer to the following pages.

Head device number storing data for which the CRC value is generated

16-bit binary

Device number storing the generated CRC value

n

Number of 8-bit (1-byte) data for which the CRC value is generated or the device number
storing the number of data

System User

Digit Specification

System User

Special 

Unit

Index

Con-
stant

Real 

Number

Charac-

ter String

Pointer

X Y M T C S D .b KnX KnY KnM KnS T C D R U \G

V Z Modify K H

E

" "

P

S

S

S

S

S

S

S

n

P

FNC 188

CRC

Mnemonic

Operation Condition

16-bit Instruction

 7 steps

CRC
CRCP

Mnemonic

Operation Condition

Continuous

Operation
Pulse (Single)

Operation

32-bit Instruction

⎯
⎯

  S

  D

  S

  D

   

S

   

D

FNC188

CRC

n

Command

input

D 

S