Setting up Limit Switchesd

[Jeff Pollard]

Hi,

  For a simple example of how to connect a limit/home/etc. switch to the DB25 breakout board (BOB), see the BOB page here:

http://xylotex.netfirms.com/OSCommerce/catalog/product_info.php?cPath=28&products_id=88

   Any questions, just ask.

Jeff

[Joel King aka Johnny Chainsaw]

Thanks Jeff. I appreciate you taking the time to help. So I can just wire the limit switches to any of the pins on the buss and the ground. And, I take it that I assign each limit to the corresponding place in Mach 3, wherever that might be. Could I also use a pin for auto Z axis zero and maybe to a relay for router on off?  If anyone could post a sketch of a wiring diagram, that a novice could understand, would be awesome. I would gladly buy somebody a cheeseburger to get me going on this. I have the xylotex 4 axis combo, the db25 BOB. I have built the Dave Gatton shoestring cnc machine. I have the jest of what to do, but every video I have watched seems to take for granted the basic starting point of actually hard wiring these devices and setting them up in Mach3. Thanks, Joel

[Jeff Pollard]

Hi,

  Any of the switch inputs need to be on the parallel port input pins (not just any pin of the DB25)
  Similarly, and relay control (output) must be on a parallel port output pin.
  An example of a switch input is shown on the BOB product page.  It's pretty simple.  Just connect 5V and GND to the BOB (like from a USB or wall wart).  Then connect your NC switch as shown in the picture.  Then you just have to set up Mach3 correctly.  Try it.  It isn't too bad, and not as hard as you might think.
  Outputs are a little more difficult as they usually require driving an interface board since the parallel port output itself is not strong enough to drive a relay by itself.  Most relay drive(interface) boards will have wiring diagrams on how to use them.

Jeff

[Joel King aka Johnny Chainsaw]

Well Allrighty then. Thanks a lot Jeff, got all home switches, E-stop, and auto Z, wired up and working today. Appreciate the help, wasn't bad at all. King

[Joel King aka Johnny Chainsaw]

well, I made my router on off controlled by Mach 3 today. Not difficult at all.

[Jim Johnson]

I have built the same cmc as Joel. was wondering what relay I could use for router on/off. Also need to know how to wire up. If Joel sees this maybe he count respond also.

[Jeff Pollard]

Hi,

  I would recommend using a SSR (solid state relay).  Get one that can easily handle the voltage of your router.  I would recommend getting one that can handle more current (Amps) than what your router is rated for (even on up to double the amount).

  If you use a SSR, then you can connect the (+) side to 5V (like from a USB port or wall wart), and the (-) side to the parallel port output pin that you decide to use.
  As for the other two terminals marked with ~, one would go to the power side of your AC supply while the other would go the the power pin of the cord to the router.  That is the right hand side pin (round ground pin down referenced), while the left hand side (neutral) would be wired straight through.

Jeff

[Jim Johnson]

should I use this relay in conjunction with the bob in order to have access to the other parallel port pins. If not how do you access the parallel port pins.

Thanks for your help.

Jim

[Jeff Pollard]

Hi,

   Yes, A BOB would make it easier to access the parallel port output signal that you want to use.

Jeff

[Jim Johnson]

Jeff,

A little more help please. I bought your BOB to do this with. I plan to use a free usb port for power. Not sure I understand completely. This is what I think is right. the + of the usb to + on the relay. a separate wire from - on the relay to DB1 which is the pin I plan to use. What happens to - wire from the usb supply. I assume to gnd on the BOB. Also, If I want to use limit switches I would put 5v to the connector on the BOB. Can it be the same as used for the relay or does it need to be a separate. Am I making any sense at all. Sorry for the bother, just don't want blow something up. 

Thanks for the help.

Jim

[Jeff Pollard]

Hi,

  The +5V for the BOB is to actively pull the input lines to a known state.  You use the +5V and GND from the USB port on the +5 and GND of the BOB.  The +5V is only important for the inputs on the BOB.  The GND will be important if you use the output signals, so it needs to be attached in any case.

  Are you using a SSR or something else?  If you are trying to drive a mechanical relay, then other things need to be considered.

   If you use an SSR as I mentioned earlier, then the +5V of the USB goes to the + side of the SSR.  The - side of the SSR goes to DB1 on the BOB.  Current will flow from the + side through the DB1 "output" through circuitry to GND.  The will cause the SSR to turn on.

  The +5 volts going to the BOB can be the same one (jumper wired over) to the SSR.

Jeff

[Jim Johnson]

Jeff,

Thanks for making it clearer for me. Yes, I am using an SSR. Actually I am going to use 2. one for the router and one for the shop vac. I now 

understand how it works. Thanks again for the help.

Jim

[Joel King aka Johnny Chainsaw]

how I wired my limit switches

[robinde...@gmail.com]

Jeff, when redirected to your link get a message of "file not found" can you repost or direct me to another example? Thanks

I'm using the BOB_DB25 board. Do you have a print of wiring switches, estop, etc to this board?

Robin

[Jeff Pollard]

Hi,

  For a selected  DB25 input, wire up one side of  your limit switch (usually NC).  Wire the other side (usually COM) to GND.
  That's it.
  The rest is controlled by software.

Jeff