Industrial switch

[deeek]

I am in need of an industrial grade switch like what the Cheesy Poofs used last year. Does anyone know where I might get something like it? Thanks!

[marshall]

LOL... Vex:

http://www.vexrobotics.com/vex/produ.../276-2159.html

[SousVide]

Originally Posted by marshall

LOL... Vex:

http://www.vexrobotics.com/vex/produ.../276-2159.html

Is there one similar to this that is wired NC ? or has the ability to be rewired without having to rebuild it ?

[Bruceb]

that would be a simple programming change

[SousVide]

Originally Posted by Bruceb

that would be a simple programming change

I hope that I didn't deviate too much off the thread. Is this about the NC wired switch ? not sure if this was something else in the thread that could be a software change ...

How would a software solution work to detect a open-wire condition in a normally NO switch ?

[nighterfighter]

Originally Posted by SousVide

I hope that I didn't deviate too much off the thread. Is this about the NC wired switch ? not sure if this was something else in the thread that could be a software change ...

How would a software solution work to detect a open-wire condition in a normally NO switch ?

Just see what the roboRIO reports back.

If the switch is normally closed:

if (!getSwitch()) //This will happen when the switch opens
{
Do stuff
}


If the switch is normally open
if(getSwitch () ) //This will happen when the switch closes
{
Do stuff
}

Obviously this is not the correct function call, but just an example of how you would code it. (I am assuming that when the switch is closed, the function will return TRUE. If it's the other way around, switch my code...)

Edit: I assumed incorrectly. According to the documentation that GeeTwo linked to, when the switch is OPEN, the value is 1, when it is CLOSED the value is 0.

[nuclearnerd]

As Al mentioned, overtravel is very important when you're slinging big masses. I recommend industrial limit switches, rather than push buttons (which are meant for humans to press, not machines). Something like this: http://www.mcmaster.com/#7988k2/=vw63cb

[GeeTwo]

Originally Posted by SousVide

.. Is this about the NC wired switch ? not sure if this was something else in the thread that could be a software change ...

How would a software solution work to detect a open-wire condition in a normally NO switch ?

This web page covers the difference between NO and NC pretty well. It's based on the 2014 control system, but I don't think any of the concepts at this level of detail have changed.

[nighterfighter]

Originally Posted by GeeTwo

This web page covers the difference between NO and NC pretty well. It's based on the 2014 control system, but I don't think any of the concepts at this level of detail have changed.

Here is the 2015 version. The only "change" is the picture of the switch is slightly brighter.

One thing to point out (and I edited my post saying I assumed wrong), is that the digital input on the roboRIO will be 1 when the switch is open, and 0 when it is closed.

Example Java code is provided in the link, and the code will be the same for C++.

[SousVide]

So, the problem that we've always have is having the limit-switches wired in a way that is failsafe. If the mechanism or action that the limit-switch is meant to stop is one that could be destructive or harmful, then if somehow the limit-switch itself fails or the wiring connecting it to the RoboRio fails (cut or is disconnected), the software won't read this limit condition and the destructive process will proceed... In this case, we like to use limit-switch that are wired as NC (and open when contact is made)... that way, if there's a failure in the limit-switch (or the wiring) it stops the mechanism from working altogether.

I don't think there's a way for a NO limit-switch to be fixed in software to detect a limit-switch failure scenario. It would look like everything is fine until when it's suppose to signal the contact.

[jman4747]

As mentioned before Automation Direct literally has industrial grade switches. Many of them have wires for both N.O. and N.C. Operation at the same time so if you wanted to tell if the switch wasn't connected you would know for sure if both N.O. and N.C. were off at the same time. And Automation Direct gave everyone a voucher for $30 and one switch runs for $24 - $28 depending on what kind.

[tr6scott]

Automation Direct.
AAP2T51Z11

$14.50 each

Limit Switch style with adjustable arm.

We are using these for overtravels on our elevator.
Plastic body means they are light as compared to other industrial switches.

[deeek]

Originally Posted by marshall

LOL... Vex:

http://www.vexrobotics.com/vex/produ.../276-2159.html

Thank you so much everyone! I thought I checked everywhere on the Vex website, but I guess I must have limited myself to the Vex Pro side. How much abuse can these take?

[marshall]

Originally Posted by deeek

Thank you so much everyone! I thought I checked everywhere on the Vex website, but I guess I must have limited myself to the Vex Pro side. How much abuse can these take?

A decent amount. Buy spares if you are worried about it.

Personally, I'm not a huge fan of the microswitches we all typically use. I'd love to see a more robust option on the market and I suspect there are but I haven't found one that I truly love yet.

[deeek]

Originally Posted by marshall

A decent amount. Buy spares if you are worried about it.

Personally, I'm not a huge fan of the microswitches we all typically use. I'd love to see a more robust option on the market and I suspect there are but I haven't found one that I truly love yet.

Ok, thank you for the information. What I've been finding, when I was trying to find that switch, was that industrial-grade switches are really expensive!

http://www.grainger.com/product/SIEM...AS01?$smthumb$
http://www.grainger.com/product/DAYTON-Momentary-ABS-WP131861/_/N-8du/Ntt-momentary+switch?nls=1&sst=subset&ts_optout=true&s _pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/30G362_AS01?$smthumb$

Originally Posted by GeeTwo

I wouldn't count on them continuing to function after stopping your robot in a crash, if that's what you're asking. When mounting "button" type limit switches, recess the switch inside or slightly behind a structural element (e.g. frame perimeter) so that the structure is taking the force of the collision before the switch reaches its stop.

Great advise! Thank you.