Application:-In electrical panel there are two switches given for panel ON
lamp. Both the switches are optional, the lamp can be OFF either by switch 1 or
switch 2.Draw truth table, electrical wiring diagram and write PLC program for
this application.
Components:-Programmable
logic controller, Electrical panel, wires, 24vDC switches with NO contacts,
24VDC indication lamp, 24 VDC relay.
Explanation:-
As
per our application, we can use the above application for the NOR gate explanation. In the application, we are using two switches and one lamp for indication. If switch 1
or switch 2 pressed, an indication lamp should be OFF. So in the above electrical
wiring diagram, we have used S1 and S2 in parallel connection so electrical
supply can flow either from S1 or S2. We have used NC contact of relay for
negative operation, hence the NOR gate.
In the truth table, we can
easily understand the conditions of NOR gate,
As per truth table,
If S1=ON OR S2=ON, then R=0
If S1=ON OR S2=OFF, then R=0
If S1=OFF OR S2=ON, then R=0
If S1=OFF OR S2=OFF, then R=1
So the output will be ON only in the last condition.
PLC
program:-
Write the ladder program for NOR gate operation
using ladder diagram language. Here for ladder logic, we can use any PLC system.
For PLC logic we need digital inputs and outputs.
For our application, all switches are digital inputs
and the lamp is a digital output. To define digital input address and output address
as per below explanation,
Digital
inputs:-
S1=I0.0
S2=I0.1
Digital Output:-
Lamp=Q0.0
Memory
coil:-
Memory bit-M0.0
PLC
program Explanation:-
In-network 1
we have considered two digital inputs for two switches S1 and S2. So we have
taken NO contact of S1 (I0.0) in parallel with S2 (I0.1) for NOR
operation. So when S1 or S2 OFF, memory bit (M0.0) will be ON.
In-network 2
we have taken NC contact of memory
bit (M0.0) to operate panel ON lamp (Q0.0).
So
ReplyDeleteThese is good
I am learning plc.
Thanks
ReplyDelete