7 APPLICATION INSTRUCTIONS
7.20 Data Processing Instructions
945
7
Processing details
• These instructions generate the CRC value for (n) 8-bit data (unit: byte) starting from the device specified by (s), and store
the CRC value to the device specified by (d). "X
16
+ X
15
+ X
2
+1" is used in the generator polynomial of the CRC value
(CRC-16). The 16-bit conversion mode and 8-bit conversion mode are available for these instructions. The conversion
mode can be selected by turning on or off SM772.
• If the value specified in (n) is 0, no processing is performed.
• These instructions calculate the CRC (cyclic redundancy check) value which is an error check method used in
communication. In addition to CRC, there are other methods to check an error, such as parity check and sum check
(checksum). For obtaining the horizontal parity value and sum check value, the CCD(P) instruction is available. (
• The operation in each conversion mode is described below.
■
16-bit conversion mode (while SM772 is OFF)
In this mode, the CRC operation is executed for upper 8 bits (in units of byte) and lower 8 bits (in units of byte) of the device
specified by (s). The operation result is stored to 16 bits in one device specified in (d).
Ex.
When (n)=6
In 16-bit conversion mode, the six bytes in the following shaded portion become an operation target. The CRC value is
determined as "A57BH", and therefore "A57BH" is stored in the device specified by (d).
■
8-bit conversion mode (while SM772 is ON)
CRC operation is executed only for lower 8 bits (lower byte) of the device specified by (s). With regard to the operation result,
lower 8 bits (in units of byte) are stored to the device specified by (d), and upper 8 bits (in units of byte) are stored to a device
specified by (d)+1.
Ex.
When (n)=6
In 8-bit conversion mode, the six bytes in the following shaded portion become an operation target. The CRC value is
"BDA1H" and therefore "A1H" is stored in the device specified by (d) and "BDH" is stored in the device specified by (d)+1.
Operation error
Error code
(SD0)
Description
3405H
A digit other than 4 is specified in the digit-specified bit device in (s) and (d).
FFH
FFH
7FH
F9H
D0
24932
D1
4219
D2
-1333
D3
-1
D4
32761
27H
10H
D5
10000
61H
61H
64H
64H
10H
10H
7BH
7BH
FAH
FAH
CBH
CBH
61H
64H
10H
7BH
FAH
CBH
Upper
Lower
Decimal
Hexadecimal
61H
64H
64H
10H
7BH
7BH
FAH
CBH
CBH
FFH
FFH
FFH
7FH
F9H
F9H
D0
24932
D1
4219
D2
-1333
D3
-1
D4
32761
27H
10H
10H
64H
7BH
CBH
FFH
F9H
10H
D5
10000
Upper
Lower
Decimal
Hexadecimal
Summary of Contents for MELSEC iQ-R Series
Page 1: ...MELSEC iQ R Programming Manual Instructions Standard Functions Function Blocks ...
Page 2: ......
Page 24: ...22 INDEX 2092 INSTRUCTION INDEX 2093 REVISIONS 2104 WARRANTY 2105 TRADEMARKS 2106 ...
Page 34: ...32 MEMO ...
Page 35: ...33 PART 1 PART 1 OVERVIEW This part consists of the following chapter 1 OVERVIEW ...
Page 68: ...66 1 OVERVIEW 1 5 Precautions on Programming MEMO ...
Page 1448: ...1446 14 REDUNDANT SYSTEM INSTRUCTIONS 14 2 Disabling Enabling System Switching MEMO ...
Page 1972: ...1970 33 TIME DATA TYPE FUNCTIONS 33 4 Division MEMO ...
Page 2067: ...APPX Appendix 5 PID Control Program Examples 2065 A 252 Set PID control data for loop 2 ...
Page 2109: ......