Programming PLC
Counter –Up
Counter -Down
Done bit is ON when Acc. >= Preset
Done bit is ON when Acc. >= Preset
Counter Reset
Programming PLC
Limit Test
Example:
Programming PLC
Equalizer
Example:
Programming PLC
Not Equal to
Example:
Programming PLC
Less Than <
Example:
Programming PLC
Less Than or Equal to <=
Example:
Programming PLC
Greater Than >
Example:
Programming PLC
Greater Than or equal to >=
Example:
Programming PLC
Greater Than or equal to >=
Example:
Programming PLC
MEQ = Masked Equal to
Example:
Output will be energized when N7:0“AND” with N7:1equals N7:5
Bit wise multiplication
Programming PLC
Scale
Example:
When Input is energized, Scaling will be done
N7:9= {N7:0x (Rate/10000)} + offset
N7:9 = {44x (5000/10000)} + 5
N7:9 = 27
Programming PLC
Square Root
Example:
When Input is energized, Square root function will be performed
N7:1= 49
N7:8 = 7 (after command executed)
Programming PLC
Negate
Example:
When Input is energized, Negate function will be performed
N7:0= 44
N7:0 = -44 (after command executed)
Programming PLC
MVM = Masked Move
Example:
When Input is energized, MVM will be performed
N7:5= N7:0bit wise AND with N7:2
Programming PLC
Copy File
Example:
When Input is energized, Copy Function will be performed
N7:0------------N7:10
N7:1------------N7:11
N7:2------------N7:12
N7:3------------N7:13
N7:4------------N7:14
Programming PLC
Fill File
Example:
When Input is energized, Fill Function will be performed
N7:0------------N7:10
N7:0------------N7:11
N7:0------------N7:12
N7:0------------N7:13
N7:0------------N7:14
N7:0------------N7:15
Note:
In Allen Bradley, Fault occurs when calculation value exceeds
32767
Math Error
Programming PLC
Flow Control Instructions
Example:
Jump & Label
Case 1: When Jump is not enabled
When I:0/5 is True/False B3:0 is On/Off
When I:0/4 is True/False B3:1 is On/Off
When I:0/3 is True/False O:0/2 is On/Off
Case 2: When Jump is Enabled
When I:0/5 is True/False B3:0 will be at last state –No effect
When I:0/4 is True/False B3:1 will be at last state –No effect
When I:0/3 is True/False O:0/2 is On/Off
Programming PLC
Flow Control Instructions
Subroutine
Jump Subroutine & Return
Main Program
Case 1: When Subroutine is not called
U:3 i.e. Subroutine program wont be scanned by CPU
Case 2: When Subroutine is called
U:3 i.e. Subroutine program starts getting scanned by CPU
Case 3: When Return is executed
Ouputof U:3 ladder get freezed& remain at that state
Programming PLC
Temporary END
Example:
When I:0/5 is energized ladder below TND is not scanned by CPU
Programming PLC
Temporary END
Example:
When I:0/5 is energized ladder below TND is not scanned by CPU
Programming PLC
Sequencer Output
Example:
Fileis the address of the sequencer file. Make sure to use the file indicator (#). This file stores the reference data for
monitoring inputs.
Maskis a hexadecimal code or the address of the mask word or file through which the instruction moves data. If
the mask is a file, its length will be equal to the length of the sequencer file. The two files track automatically.
You can enter the code in binary, decimal, or hexadecimal.
Destinationis the address of the output word or file for a SQO to which the instruction moves data from its
sequencer file.
Controlis the instruction’s address and control element (3 words) that stores the status byte of the instruction, the
length of the file, and the position in the file. Do not use this address for any other instruction. Status bits in the
control file include
Lengthis the number of steps of the sequencer file starting at position 1. Maximum = 255 words (104 words when
using the MicroLogixcontroller). Position 0 is the startup position. The instruction resets (wraps) to position 1 at each
cycle completion.
Positionis the word location or step in the sequencer file from/to which the instruction moves data. A position value
that points past the end of the programmed file causes a runtime major error to occur.
Programming PLC
Sequencer Output
Example:
Programming PLC
Sequencer Compare
Example:
R6:3/FD is bit which is ON when comparison is TRUE
i.e. When I:0.0 masked with B3:1 & result equals B3:0
This command can be used for diagnostic purpose such that to check
Whether specified inputs are ON or OFF at various stages of sequence
Ex Homing, Station 1, Station 2 etc.
Programming PLC
Sequencer Load
Example:
This command stores the status of Inputs at N7:0 till number of position
mentioned. In this case uptoN7:4
Position 1 N7:1
Position 2 N7:2
Position 3 N7:3
Position 4 N7:4 Values get over rite when cycle completes