View Full Version : Proximity switches

03-16-2008, 10:40 PM
All my proximity switches are lit up except when the pass near the sensors. Is this right? When trying to set up the zero using proxi switches it wont go/run as it says one of the proxi switches is triggered ... I have even moved the router and x car to the center of the table ...


03-17-2008, 10:19 AM
The Proximity switches for the PRS machines are normally ON all the time, except when they sense the target, then they turn off. Be sure that you've configured the switches correctly with the VN command (Normally Closed)

03-19-2008, 10:53 PM
ok, This is resolved. My issue was that I had set the proxi switches exactly on the zero mark.

05-26-2008, 08:36 AM
My proximity switches stay on until they come in contact with the targets and then they go out...the problem I have is that when I test them according to the manual, they go beyond the targets...help

05-26-2008, 05:14 PM

Check to make sure that "Limits" are "On". Hit VN and set them to "On" if they aren't.

05-27-2008, 08:18 PM
they are on Scott...any other ideas??

05-28-2008, 12:15 PM
Make sure you have them wired per the manual. Validate that the "green light" image in the shopbot software turns red when the actual light goes out on the switch.

05-29-2008, 09:53 AM
From the manual:

"• Use the KeyPad to back off the Proximity Switch. The LED should come back on. You
can test the “Limit” Function of the Proximity Switches with the KeyPad. First use the
[VN] Command to turn the Limit Switch functionality on. Now use the KeyPad to
drive into the switch. Your tool should stop. After hitting a switch, the KeyPad then
overrides switches if you use it again, so you can drive off the switch. After you have
driven off and released the arrow key. The switches will again function as limits."

You must let off the button after moving off the prox switch to reset the switch to work again.

06-15-2008, 01:09 PM

I just received (Friday) my BT48, and all is going well. It's been uncrated, set in position, leveled, and now I'm going through "air motions".

One question about proximity/limit switches. Can you drive to "any" location without damage? I mean, do the proximity switches provide constant protection, or are they only a way to give a hint you're about to overrun travel in a given direction?


Gary Campbell
06-15-2008, 02:15 PM
Assuming setup as per instructions, the prox switches will work to bring the machine to a dead stop upon activation. This will work during both slow and fast moves. (dont ask how I know this) Make sure that there is the recommended distance from the prox's to the hard stops.

06-15-2008, 05:07 PM

How do I make sure I've got the "recommended distance"? O.K., it's probably in the manual...


P.S. When I did my first "air moves", using "MZ3" would result in some noise/chattering as the Z axis limit was reached. (If I understand correctly, the Z axis range is [-3,+3], inclusive. So, entering "MZ4" should cause a limit switch to be activated resulting in Z motion stopping?

Gary Campbell
06-15-2008, 05:41 PM
My PRSa does NOT have a limit switch on the Z axis. Not sure about your setup. If you reach the Z limit, in either direction, you should experience a motor/driver fault and have to reset.

10-26-2009, 11:13 PM
Are the limit switches provides with purchase?
If so, are they magnetic or proximity switches or are they micro switches requiring actual contact?

If not provides with a machine, what is recommended?

Gary Campbell
10-26-2009, 11:18 PM
Prox switches (limit switches) are provided for the X & Y axes on a new machine. They are inductance proximity switches that sense a target bolt head that you can adjust.

They are used for setting a relative 0,0 position in X & Y and for stopping an erroneous move before the gantry hits the hard stops. Instructions are included with the machine.

10-27-2009, 12:37 AM
Thanks Gary!
Got it.
3 wires?
NO NC and Neutral?

10-27-2009, 10:32 AM
I have lever trip switches now. Are the prox switches more repeatable/accurate?


Gary Campbell
10-27-2009, 02:46 PM
You are thinking of analog NO/NC configuration. These are digital NPN NO configuration. 3 wires are +24v, -24V and signal, which is sunk from small positive voltage.

Cant give a definative answer, but over the long run the electronic switches should give better results, longer life, and equal or better accuracy.