Help implementing relay logic
- Thread starter mikas_m
- Start date
AMAZINGAHMED
Member
Can I ask why you put the M3.0 +ve edge?
Because, I want my circuit to behave like that. I want whole circuit to be in Run mode only when there is a transition of start signal from 0 to 1. in other words I want stop contact to break circuit even if start is still pressed and to start again when start is releasd and pressed again i.e. when there is a positive edge.
manmeetvirdi
Member
hi there
Two push buttons one with NO element(for starting motor) and other with NC element(for stopping the motor) and a contactor of appropriate amps size will do.
Do search for DOL CIRCUIT in Google.
Two push buttons one with NO element(for starting motor) and other with NC element(for stopping the motor) and a contactor of appropriate amps size will do.
Do search for DOL CIRCUIT in Google.
rsdoran
Lifetime Supporting Member
mikas_m said:Hello,
can you help me implemetning the logic showed as ladder rung in the following picture?
I need to realize it with classical and timer relays.
Can you give me any suggestions?
Thanks
Hardwired with relay (starter) this if fairly straightforward.
When hardwired the Stop pushbutton is normally closed i.e. the power goes thru it to the start button; therefore if Stop is pushed then Start can not do anything.
http://www.patchn.com/motors.htm
This is a standard, 100 years old or more, motor control ckt.
BTW, there would be no need for a one-shot for this when programming a plc. ALSO, the STOP button should be N.O. in the code BUT the physical switch should be normally closed.
Last edited:
sinanissa
Member
I suppose it is a great idea
you can use a timer of 0.5 sec or less as follow:
start . . . . . . . . . . . . . . timer
--] [-------------------------------( )---
start . timer . . . . stop . . . . .Run
--] [----]/[-----------]/[----------( )---
. Run . . . . .|
--] [----------|
you can use a timer of 0.5 sec or less as follow:
start . . . . . . . . . . . . . . timer
--] [-------------------------------( )---
start . timer . . . . stop . . . . .Run
--] [----]/[-----------]/[----------( )---
. Run . . . . .|
--] [----------|
Last edited:
rsdoran
Lifetime Supporting Member
Why?
Well, this is not for the motor. I made this looks simalr to get a lot of ideas. Basically, start is relay contact from elswhere which can "start" some other logic. I want to use "stop" as NC pushbutton (when user press, it breaks connection) to some kind of "acknowledge", so to end "run" even if condition to start is still present. i have currently implemented this exactly like sinanissa. Timer is more expensive component, but I guess it is necessary.
Thank you all for your suggestions.
Thank you all for your suggestions.
HI,
I think it's a good circuit to prevent the operators from jamming a screwdriver or pocket kinfe into the start push button & walking away. Do you need this circuit hard wired, or programmed? There are hardwaer timers available that have a one shot function. When the timer input goes true even for a brief period, their output contacts will close for an adjustable amount of time. When that time expires, the contacts will open. The timer won't close the contacts again until there is a false to true transition on it's input. In ladder logic you may want to use a timer triggered by the start button, then use the timer timing bit for a start --| |-- in the next rung.
BD
I think it's a good circuit to prevent the operators from jamming a screwdriver or pocket kinfe into the start push button & walking away. Do you need this circuit hard wired, or programmed? There are hardwaer timers available that have a one shot function. When the timer input goes true even for a brief period, their output contacts will close for an adjustable amount of time. When that time expires, the contacts will open. The timer won't close the contacts again until there is a false to true transition on it's input. In ladder logic you may want to use a timer triggered by the start button, then use the timer timing bit for a start --| |-- in the next rung.
BD
PeterW
Member
Don't need a timer
For the life of me I can't see why you would want this though, what's wrong with the good old fashioned way, where you have a spring return pushbutton.
For the life of me I can't see why you would want this though, what's wrong with the good old fashioned way, where you have a spring return pushbutton.
PeterW
Member
I should have read the explanation of why you wanted it...
also my mistake
the link up to R1 should be between the Start and the N/C R1 contact, no after the R1 contact.
Therefore once pressed and R2 comes in, R1 retains until the start is released.
also my mistake
the link up to R1 should be between the Start and the N/C R1 contact, no after the R1 contact.
Therefore once pressed and R2 comes in, R1 retains until the start is released.
PeterW
Member
You can tell its a long time since I designed hardwired circuits
As well as moving the connection for the R1 coil, should also add a n/c R2 contact otherwise R1 would go mad.
As well as moving the connection for the R1 coil, should also add a n/c R2 contact otherwise R1 would go mad.
bernie_carlton
Lifetime Supporting Member + Moderator
Peter - depending on the structure of the contacts for R2 this may not work. Standard relays will unmake one set of contacts before making the opposite set. The NC contat from R2 may unmake before the NO can make sealing the circuit. I think you'll just have a buzzer.
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