Time delay relay with pass-thru... I think...

Thread Starter

Rob@FAM

Joined Aug 13, 2017
2
Hi everyone. I'm not even sure what this would be called so I'm calling it a relay for lack of a better idea and lack of understanding.

I have a piece of equipment that gets turned off each night and turned on each morning. Each time it gets turned on it needs to be homed which also sets zero position. To do this you must hold a button for at least 3 seconds.

The problem is if I have a new or forgetful person on the machine they will often forget to home it after turning it on, and won't do it until the next setup... where invariably they realize their mistake and get to do the previous jobs again.

So, what I need is a device that once power is applied to the machine it will wait a moment (like less than one second) and then "press" that button for at least three seconds (can be a little longer as long as it stops pressing). I was thinking some kind of relay would work for this but....

During the course of the day the machine may need to be reset. So basically they may need to press the button again and then hold the button for three seconds without this relay interferring.

I'm not even sure where to begin on this, and unfortunately the guy who assembled/built this machine some time ago is no longer around. Given that I normally just maintain things I'm in over my head, but the boss told me to get it figured out.

Any help would be appreciated.
 

LesJones

Joined Jan 8, 2017
3,136
Am I correct in assuming that the reset button drives an axis (Or more than one axis) to a home position where it is forced to stop either by stalling the motor or operatiing a limit switch and at that point the DRO readout for that axis is set to zero ? If this is so I would use a small microcontroller such as an ATtiny13 or a PIC12F1822. It also could be done using two NE555s.

Les.
 

strantor

Joined Oct 3, 2010
5,540
what I need is a device that once power is applied to the machine it will wait a moment (like less than one second) and then "press" that button for at least three seconds (can be a little longer as long as it stops pressing). I was thinking some kind of relay would work for this but....
So you want this machine to start moving as soon as it's powered on? That doesn't sound safe.
How about an annoying alarm that comes on as soon as power is applied, and doesn't turn off until the machine is homed?
 

strantor

Joined Oct 3, 2010
5,540
So you want this machine to start moving as soon as it's powered on? That doesn't sound safe.
How about an annoying alarm that comes on as soon as power is applied, and doesn't turn off until the machine is homed?
Sorry I don't have time to wait for a reply. about to leave. So I'll tell you how to do what I described:
Install a relay with power going through a NC contact to a sonalert or other light stack or siren.
As soon as you power the machine on, this relay will be deenergized so the alarm will be on.
Now jumper the output of the home switch from wherever it's going, to your relay coil.
Wire your relay in a latching configuration so that once the machine moves off the home switch the relay stays energized so the alarm stays off.
Once the machine is shut down the relay will deenergize and when you turn it back on, alarm will turn back on.

Wire it just like this except without the stop button

The "start" button would be your home switch.
CR1 could be a NC contact instead of the NO contact shown.
The "light" would be your alarm.
 

Reloadron

Joined Jan 15, 2015
5,916
My first suggestion would be remove and replace operator with a known good unit. Next suggestion would be place a placard on the machine with the daily startup procedure. Finally rather than do this electronically I like strantor's suggestion using an alarm which comes on at startup and remains on till an operator clears it.

Yes, it can be done electronically but a simple startup procedure and audible alarm is the simplest method.

Ron
 
Not that I like the idea, but maybe the 3 sec push is there for a reason? It catches early issues?

Could always generate say a 15 s delay and turn on a strobe if the button isn;t pressed. It would get someone's attention.

You have to interface to something and need to know what that something is.

Instead of building stuff you don;t understand, "black boxes" are readily available. Delay on make, delay on break and multipurpose timers exist.

To get your "feet wet see SSAC line of timers: https://www.google.com/url?sa=t&rct...rs.pdf&usg=AFQjCNFadKaGnJjPr49T5u-fwK0opxvecA

You could also consider light such as these: http://www.ledandon.com/stack_light...MIx9rMpvjX1QIVRbbACh3X_gubEAQYAyABEgKgd_D_BwE

Red might be "Not Reset"; Yellow "Operating"; Green "Stopped" It's just an idea.

I wouldn't use the voice module that says "Yo Fred! Reset the machine! ".
 
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