Mitsubishi Electric MELSEC FX Series - 7.18.4 CRC

7 Applied Instructions
7.18 Others
605
FXCPU Structured Programming Manual
(Basic & Applied Instruction)
1
Outline
2
Instruction List
3
Configuration of Instruction
4
How to Read Explanation of Instructions
5
Basic Instruction
6
Step Ladder Instructions
7
Applied Instructions
8
Interrupt Function and Pulse Catch Function
A
Relationships between devices and addresses
7.18.4 CRC
Outline
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 instruction is available. CRC instruction uses
"X
16
+ X
15
+ X
2
+ 1" as a polynomial for generating the CRC value (CRC-16).
1. Format and operation, execution form
2. Set data
3. Applicable devices
S: Refer to "Cautions"
FX3U(C) FX3G FX2N(C) FX1N(C) FX1S FXU/FX2C FX0N FX0(S)
Instruction
name
Operation
Execution
form
Expression in each language
Structured ladder ST
CRC 16 bits Continuous CRC(EN,s,n,d);
CRCP 16 bits Pulse CRCP(EN,s,n,d);
Variable Description Data type
Input
variable
EN Execution condition Bit
Head device storing data for which the CRC value is generated ANY16
Number of 8-bit (byte) data for which the CRC value is generated or the
device storing the number of data
ANY16
Output
variable
ENO Execution state Bit
Device storing the generated CRC value ANY16
Operand
type
Bit Devices Word Devices Others
System user Digit specification
System
user
Special
unit
Index
Cons
tant
Real
Number
Character
String
Pointer
XYMTCS
D
.b
KnX KnY KnM KnS T C D R
U\G
V Z Modifier K H E
""
P
SS SS
zzz z z z
SSS
zzz z z z
zz zz
CRC
EN ENO
d
s
n
CRCP
EN ENO
d
s
n