Allen Bradley Bitwise Logical Operations

To study the working of Allen Bradley Bitwise logical operations like AND, OR, NOT, XOR in Programmable logic Controllers (PLC).

Contents

Bitwise Logical Operations

Block Name: Bitwise AND

In the above picture, there are totally three parameters,

SOURCE A – Address of First Binary Value

SOURCE B – Address of Second Binary Value

DESTINATION –AND operation result of Source A & B stored in this address

Block Name: Bitwise OR

In the above picture, there are totally three parameters,

SOURCE A –Address of First Binary Value

SOURCE B –Address of Second Binary Value

DESTINATION –OR operation result of Source A & B stored in this address

Block Name: Bitwise XOR

In the above picture, there are totally three parameters,

SOURCE A –Address of First Binary Value

SOURCE B –Address of Second Binary Value

DESTINATION –XOR operation result of Source A & B stored in this address

Block Name: Bitwise NOT

In the above picture, there are totally two parameters,

SOURCE -Address of Binary Value

DESTINATION –NOT operation result of Source stored in this address

PLC LADDER EXAMPLE

Working of Bitwise logical operation in AB PLC

CASE 1:

When,

Source A : 0000 0000 0000 0000 (AND,OR & XOR)

Source B : 0000 0000 0000 0000 (AND,OR & XOR)

Source : 0000 0000 0000 0000 (NOT)

Rung 0000:

All Bitwise operator block are connected in parallel with input condition I: 0/0. When it goes ON, each block performs its operation. Since Source addresses are having zeros except NOT block remaining blocks are resulting 0s.

BITWISE Operation of AND, OR, XOR, NOT:

AND Logic:

Source A : 0000 0000 0000 0000 (B3:0)

Source B : 0000 0000 0000 0000 (B3:1)

Destination : 0000 0000 0000 0000 (B3:2)

OR Logic :

Source A : 0000 0000 0000 0000 (B3:0)

Source B : 0000 0000 0000 0000 (B3:1)

Destination : 0000 0000 0000 0000 (B3:3)

XOR Logic :

Source A : 0000 0000 0000 0000 (B3:0)

Source B : 0000 0000 0000 0000 (B3:1)

Destination : 0000 0000 0000 0000 (B3:4)

NOT Logic :

Source: 0000 0000 0000 0000 (B3:0)

Destination : 1111 1111 1111 1111 (B3:5)

DATA FILE FOR CASE 1:

CASE 2:

When,

Source A : 0010 0101 0100 0001 (AND,OR & XOR)

Source B : 0001 0001 0001 0001 (AND,OR & XOR)

Source :0101 0100 1000 0111 (NOT)

Rung 0000:

I:0/0 giving input condition to all Bitwise Blocks. When it goes ON, value placed in Source A and Source B performs respective operation depends on blocks.

BITWISE Operation of AND, OR, XOR, NOT:

AND logic:

Source A : 0010 0101 0100 0001 (B3:0)

Source B : 0001 0001 0001 0001 (B3:1)

Destination : 0000 0001 0000 0001 (B3:2)

OR Logic:

Source A : 0010 0101 0100 0001 (B3:0)

Source B : 0001 0001 0001 0001 (B3:1)

Destination : 0011 0101 0101 0001 (B3:3)

XOR Logic:

Source A : 0010 0101 0100 0001 (B3:0)

Source B : 0001 0001 0001 0001 (B3:1)

Destination : 0011 0100 0101 0000 (B3:4)

NOT Logic:

Source: 0101 0100 1000 0111 (B3:0)

Destination : 1010 1011 0111 1000 (B3:5)

DATA FILE FOR CASE 2:

Conclusion:

We can use this explanation to understand the working of Bitwise logical operation like AND, OR, NOT, XOR in Allen Bradley Programmable logic Controllers (PLC).

Author : Hema Sundaresan

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