OR Gate Logic in PLC

PLC OR Gate

• We representing a OR Logic Gate with two Inputs A and B.

OR Gate

• OR Logic gate Input A OR Input B must be on for the Output.
• We use 1 to indicate an on signal and 0 to represent an off signal. So we consider output as 1 must have A OR B consider 1.

OR Gate Truth Table :

Inputs		Output
A	B
0	0	0
0	1	1
1	0	1
1	1	1

PLC OR Logic :

• Ladder diagram starts with a normally open set of contact Input A, to represent switch A and in parallel with normally open set of contact Input B, to represent switch B.
• Terminates with O represent the output. For output on both Input A OR Input B contacts have to be closed.

  

  PLC OR Gate Logic