Double acting cylinder, single acting solenoid A+B+B-A-

Copyleft

Member
Join Date
Aug 2017
Location
Kusatsu
Posts
15
Hi, guys.

At first sorry for my english, im not english speaker.

Im trying learn ladder and i cant figure out this sequence;
i have 2 push buttons, 1 NO and another push button NO/NC;
4 reed switches A-A+B-B+
2 double acting cylinders
2 single acting solenoids
push button NO start cylinder A;
A+ (reed switch) active cylinder B;
B+ (reed switch) hold the A and B cylinders until i press NC/NO push button;
button pressed cylinder B retracted;
B- activated retracted cylinder A

I can make the sequence A+B+ and hold both cylinders but i cant figure out how to retracted in sequence B-A- and hold until i press start again.

Its possible to make this sequence work using single acting solenoids and double acting cylinders?
I can make this sequence work the way i want but the relay output (LEDS) start blink fast ON/OFF intermittently fast, its okay?
i brought one used PLC to learn at home because for me is more easy instead use just simulator, i can make timers, counters, basic stuff but im really stucked in this problem.
Thank you guys any direction will be welcome.
 
I am not to sure what you mean by single acting solenoids.
Are the single acting solenoids each driving a 5 port, 2 position, spring return valve?
If so, then yes it is possible.

Ideally they would not blink fast on off really fast. Relay outputs have limited number of cycles, as do the electrical components they are attached to.

Have you drawn a state machine of your logic?

Is it important to your process what happens if they hit the NO button before it is finished retracting? Also the NC/NO button before it has finished extending?
 
Hey, Copyleft welcome to the forum. I just did a project with 2 cylinders alternating extending and retracting. Although they used a position controller with pressure (servo) the logic commands activated the servo instructions for extending and retracting. So the commands to extend and retract were like your buttons. I used an extend command and an extend status ("Cyl_1_Extended") etc to help condition the logic to allow the cylinders to alternate with each other. If one was retracted before the other was completely extended, it would hold in retracted position until the other cylinder was extended and started retracting. Mostly because of valves I had to have logic switch over (open and close)
So your buttons are like the commands, the reed switches are like your statuses. As previously mentioned, use latching circuits to help you. Good luck and don't give up. Again, welcome.
 
Last edited:
Thank you guys for the ideas.
Sorry for late reply my wife had a babe few days ago and we are very busy, first time father.
Things are working now A+|B+|B-|A-
i think i get now how to use internal relay and latch, need to programming more to memorize all stuff.
Next step ill try to control stepper motor to see what happens.
 

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