Fnc188 - Crc / Cyclic Redundancy Check - Mitsubishi FX3G Series Programming Manual

FX /FX /FX /FX
3G 3U 3GC 3UC
Programming Manual - Basic & Applied Instruction Edition
24.4 FNC188 – CRC / Cyclic Redundancy Check
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 (FNC 84) instruction is available.
CRC instruction uses "X
1. Instruction format
FNC 188
CRC
2. Set data
Operand Type
S
D
n
3. Applicable devices
Bit Devices
Oper-
and System User
Type
X Y M T C S D .b KnX KnY KnM KnS
S
D
n
: Make sure to specify four digits (K4
Explanation of function and operation
1. 16-bit operation
CRC value is generated for "n" 8-bit data (unit: byte) starting from a device specified in
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.
16 15 2
"X + X + X
Command
input
FNC188
586
Series
16 15 2
+ X + X + 1" as a polynomial for generating the CRC value (CRC-16).
Mnemonic
16-bit Instruction
P
CRC
7 steps
CRCP
Head device number storing data for which the CRC value is generated
Device number storing the generated CRC value
Number of 8-bit (1-byte) data for which the CRC value is generated or the device number
storing the number of data
Digit Specification
+ 1" is used as a polynomial for generating the CRC value (CRC-16).
S
D
CRC
24.4 FNC188 – CRC / Cyclic Redundancy Check
→ For CCD instruction (check code), refer to Section 16.5.
Operation Condition
32-bit Instruction
Continuous
Operation
Pulse (Single)
Operation
Description
Word Devices
Special
System User
Unit
T C D R U \G
) when specifying the digits of a bit device.
n
24 Others – FNC181 to FNC189
Mnemonic Operation Condition
⎯
⎯
Others
Con- Real
Index
stant Number
V Z Modify K H E
S , and stored to
Data Type
16-bit binary
Charac-
Pointer
ter String
" " P
D .