Thread: Which Type of Limit Switch
That BoB, I believe is powered either from the USB lead or a separate 5v input. There will be a switch on the board or a jumper to select which. The BoB doesn't put 5v out AFAIK.
Yes, as long as they switch to ground and don't have an internal pullup. You can check this by measuring the voltage between the black and blue wires when they are powered up. If it's always zero or there abouts then you can without any other parts. If there is volts then you need a resistor between the black wire and the Bob.
Last edited by EddyCurrent; 18-07-2014 at 09:13 AM.Spelling mistakes are not intentional, I only seem to see them some time after I've posted
Here you go ray this might help. (Provided Switch can use 36V)
Don't put the switches in middle because if your on wrong side of switch when you click home then mach will never see the switch.
Mach only homes in the direction set in it's parameters IE Home NEG or Home Positive direction. So lets say you always home Negative but your already on the negative side of the switch then Mach will never see the switch and crash the limits. If you position the switches at the ends of travel then Mach will always see the switch.
Now you can still have your ZERO home position in the centre of table just you use MACH's HOME OFF(set) feature and define ZERO a set distance away from the switch. Mach will enter this amount into it's DRO so now your MACHINE coordinates will display a Negative number and when you send to Zero the table will go to the centre of travel which is MACHINE ZERO.
MACHINE ZERO won't be at the ends where table stops but the MACHINE ZERO coordinate will be in the centre of travel and all WORK coordiantes will be Referenced from this position so it works just like has if the switch was in centre.
Last edited by JAZZCNC; 17-07-2014 at 09:07 PM.
Eddy, Jazz and myself have all said the same thing, and any supply to the switch between 10 and 36 volts will work.
The only reason I'm being slightly pedantic and suggesting you do some basic voltage checks is to avoid any issues or disappointment. Chinese supplied products can vary in subtle ways especially stuff on ebay. That switch comes in 2 variants. One is truly just a switch to ground and that's what you need. The other version has an internal pull-up resistor to the +v supply and if it's that version then there is a chance you could damage the BOB if you don't have a resistor between switch and input. All I'm saying is do the electrical equivalent of 'measure twice, cut once' :)
Ray This is why I postedJust a thought although all of the above is correct are we assuming that the sensor has a resistor built in of say about 10K If not would it be prudent to put a current limiting R in.. My sensors have 10K internal so not needed.
I got these from your earlier threads;
It looks like your power supply is this one;
You are using the 36v to power the steppers and the 5v to power the breakout board, you also have a 24v supply in there for the Pilz ?
Because the 36v is used for the steppers I would suggest not using that for the proximity switches as it could contain a lot of electrical noise, instead I would use the 24v supply provided it is DC and not AC.
Also, off topic, have you cut any of those nuts yet ? what tooling do you intend to use for a 9 gauge string slot ?
Last edited by EddyCurrent; 18-07-2014 at 09:17 AM.Spelling mistakes are not intentional, I only seem to see them some time after I've posted
This is maybe a daft question, but do not see a 24v supply for the PILZ unless it is that box to the left of it on the DIN rail.
What do these safety relays do that makes them cost £360? I can see a 4 pole contactor, which is presumably 3 phases and aux and I also presume there is some sort of RCCB and E-stop interface. If you are not running 3-phase, then it seems an overkill ('scuse the ironic pun).
An RCCB a break switch and NVR switch in series, would seem all that is needed for a good level of safety on single phase 240v.
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