Problem Diagram
Problem Solution
Use limit switches, control valves and motor agitators separately for all three mixing tanks.
The only common input to all these tanks is Material feeding by two valves.
Use separate timers for each tank for mixing.
First two tanks are tagged as primary mixing tanks and the third one is said to be secondary mixing tank.
Use switches of stop buttons of both Primary mixing processes as an input to start the tank third to enter into
the process sequence.
PLC Program
Here is PLC program to Control Three Mixing Devices in a Processing Line, along with program
explanation and run time test cases.
List of Inputs and Outputs
I:1/14
= Start
(Input)
I:1/15
= Stop
(Input)
O:2/15
= Master Coil
(Output)
I:1/0, I:1/5, I:1/7
= Level of Material B Switches
(Input)
I:1/1, I:1/4, I:1/8
= Level of Material A switches
(Input)
I:1/2, I:1/3, I:1/6
= Low Level Switch (empty tank)
(Input)
O:2/0, O:2/4, O:2/8
= Inlet Valves to feed Material A (Output)
O:2/1, O:2/5, O:2/10
= Inlet Valves to feed Material B (Output)
O:2/2, O:2/6, O:2/9
= Agitator Motors M1, M2 and M3
(Output)
O:2/3, O:2/7, O:2/11
= Outlet Valves for product outlet
(Output)
T4:0, T4:1, T4:2
= Timers to mix materials
(Timer)
Ladder
Diagram
for
Mixing
Tank
1
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