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Step 5PLC, Program, and Wiring
The Pandemic Ventilator Project
The PLC unit is a Direct Logic 06 DO-06DR from Automation Direct. Automation Direct
Their units are low cost, flexible enough and they have a lot of free software to program with.
You could use other PLC units and write your own control program. If you do. please share your work at The Pandemic Ventilator Project so that others can use your program and insights as well.
Besides the PLC you will also need a 24V power supply, and an on off switch to start the system.
Program
Also below is the ladder logic program that runs the unit. (My son does the programming) As I said it is still very rudimentary. It will require some improvement to make it more stable. The program will also have to be extended to accept the inputs from the future manometer, and also incorporate safety systems and alarms.
Basically what it does is:
It opens valve 1 and closes valve 2 until the bellows is full which is indicated when the top magnetic switch closes.
It then closes valve 1, opens valve 2 and closes valve 3 so that the bellows can deflate and pump the air to the patient.
When the bellows drops to the lower limit, the lower magnetic switch closes and then valve 2 closes and valve 1 opens again to refill the bellows.
A timer lets the patients lungs deflate with valve 3 open. When the timer expires, valve 2 opens and valve 3 closes to start the next respiration cycle.
In the future I hope to get the manometer to be able to control the respiration cycles as well as the timer.
Wiring
Everything is wired back to the PLC connectors and power supplies..
My unit has all NC valves so the program should be slightly different if you use a NO valve for valve 3 as I recommended. Also I used all 120V valves. If you use 24V valves, then the output CO will be connected to 24V instead of 120V and the output returns would be connected to the 24V ground. Here is the wiring chart.
INPUTS
X0 Top bellows mag switch
X1 Bottom bellows mag switch
X2 on off switch
C0 24V
All returns to Ground
Outputs
Y0 Unused
Y1 Inhale valve (V2)
Y2 Exhale valve (V3)
Y3 Bellows fill valve (V1)
C0 120VAC line
All returns to line Neutral
The PLC unit is a Direct Logic 06 DO-06DR from Automation Direct. Automation Direct
Their units are low cost, flexible enough and they have a lot of free software to program with.
You could use other PLC units and write your own control program. If you do. please share your work at The Pandemic Ventilator Project so that others can use your program and insights as well.
Besides the PLC you will also need a 24V power supply, and an on off switch to start the system.
Program
Also below is the ladder logic program that runs the unit. (My son does the programming) As I said it is still very rudimentary. It will require some improvement to make it more stable. The program will also have to be extended to accept the inputs from the future manometer, and also incorporate safety systems and alarms.
Basically what it does is:
It opens valve 1 and closes valve 2 until the bellows is full which is indicated when the top magnetic switch closes.
It then closes valve 1, opens valve 2 and closes valve 3 so that the bellows can deflate and pump the air to the patient.
When the bellows drops to the lower limit, the lower magnetic switch closes and then valve 2 closes and valve 1 opens again to refill the bellows.
A timer lets the patients lungs deflate with valve 3 open. When the timer expires, valve 2 opens and valve 3 closes to start the next respiration cycle.
In the future I hope to get the manometer to be able to control the respiration cycles as well as the timer.
Wiring
Everything is wired back to the PLC connectors and power supplies..
My unit has all NC valves so the program should be slightly different if you use a NO valve for valve 3 as I recommended. Also I used all 120V valves. If you use 24V valves, then the output CO will be connected to 24V instead of 120V and the output returns would be connected to the 24V ground. Here is the wiring chart.
INPUTS
X0 Top bellows mag switch
X1 Bottom bellows mag switch
X2 on off switch
C0 24V
All returns to Ground
Outputs
Y0 Unused
Y1 Inhale valve (V2)
Y2 Exhale valve (V3)
Y3 Bellows fill valve (V1)
C0 120VAC line
All returns to line Neutral
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