L9_CKSM: Check Sum
(Original Document)
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Naming
Name in LL984 Editor
Function Block Name
name of legacy 984 instruction
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Function Description
The L9_CKSM EFB allows you to program 4 types of checksum calculation in LL984 ladder logic:
Representation
Parameters
Input Pin
Name
Data Type
Address Range
Meaning
Top
IN
BOOL
–
ON = initiates checksum calculation of source table
For more information see Input Parameters below.
Middle
CKSM1
BOOL
–
ON = CKSM select 1
For more information see Input Parameters below.
Bottom
CKSM2
BOOL
–
ON = CKSM select 2
For more information see Input Parameters below.
Node
Node
Name
Data Type
Address Range
Meaning
Top
IN
SOURCE
ANY_ARRAY_UINT
%MW
source
first %MW word in the source table
The checksum calculation is performed on the words in this table.
Middle
INOUT
RES
ArrUInt2
%MW
result/count
first of two contiguous words
RES[1]: result of check sum calculation
RES[2]: number of %MW words from the source table used for checksum calculation
valid range: 1 .. LENGTH
Bottom
IN
LENGTH
UINT
1...255
length
number of %MW words in the source table
valid range: 1 to 255
Position
Name
Data Type
Address Range
Meaning
Top output
OUT
BOOL
–
ON = checksum calculation succeeded
(Echoes the status of the IN input).
Middle output
ERR
BOOL
–
ON = RES[2] count > length or RES[2] count =0
Input Parameters
The states of the input parameters indicate the type of checksum calculation to be performed:
Checksum Calculation
IN
CKSM1
CKSM2
Straight Check
ON
OFF
ON
Binary Addition Check
ON
ON
ON
CRC-16
ON
ON
OFF
LRC
ON
OFF
OFF