Thread: Home Switch Problem
Hybrid View
-
21-03-2017 #1
Hi all, i'm having problems with the wiring of my home switches, mach 3 doesn't seem to recognise them in the diagnostic screen but they are working, but incorrectly, you have to press the the switch a couple of times before the axis stops. at the moment they are connected up open circuit, so when the switch is pressed it becomes live i have swapped the wires but to no avail. I have no idea whats going on and i'm not sure how to configure mach 3 with regard to the inputs and outputs etc
The switch is a mechanical lever type as shown. any help would be most appreciated
one wire goes to earth in the control box and the other is pin. pins used are X=13 Y=12 Z=11Last edited by Kev2960; 21-03-2017 at 08:21 PM. Reason: pin numbers added
-
21-03-2017 #2
Hi Kev
what breakout board are you using ?
and how have you wired the switches ?
it looks like you have wired the switches as normaly open
( if a wire breaks the control will never see a switch close ! )
JohnLast edited by john swift; 21-03-2017 at 09:23 PM.
-
21-03-2017 #3
Hi John the bob looks like this. I have tried both normally open and normally closed
-
21-03-2017 #4
looking at the breakout boards inputs
when the limit switch is closed, the EL817 opto isolator's NPN transistor will ground the printer ports input pin
the breakout board does not have any pull up resistors to ensure a printer port input is at a valid logic high when the limit switch is open
this can be a problem with PC's or laptops with 3.3V printer ports
John
-
24-03-2017 #5
Going back to this photo, my calcs based on the 1k resistor, means the opto should have 24V on the pin you've marked as 5V. At 5V, the 1k resistor would limit the current to roughly 3mA, whereas 24V would give roughly 22mA. Having had a look at the datasheet for the opto, it's expecting 20mA with a forward voltage of 1.2V.
Kev, have you measured the voltage at the top left pins on the optos?
Try using the bottom pin on the connector for gnd, and also the main power in gnd for the voltage measurements, just in case it's a gnd fault, not a positive supply fault.
If there is no voltage showing, is there power at the fan connector/is the fan working?
Would it be possible to get a photo of the underside of the board, so we can see where the power supply feed to the opto comes from?
Given the layout, I'd think the optos would take a feed from the same supply going to the fan connector, but without seeing the underside of the board, that is purely a guess.Avoiding the rubbish customer service from AluminiumWarehouse since July '13.
-
21-03-2017 #6
Hi John, Im afraid I don't understand a word of what you've just said.....sorry!
Could explain please
-
21-03-2017 #7
Hi Kev
your micro switches are connected to your PC/Laptop printerport via opto isolators
(opto isolator part number EL817 - the terminal E goes to ground and C to the printer port input pin )
do you have a multi-meter to measure the voltage change at the printer port input pin when the switch is operated ?
how have you set up the switches in mach3's ports & pins ?
any thing like this -
JohnLast edited by john swift; 21-03-2017 at 11:33 PM.
-
21-03-2017 #8
Yes I've set the ports & pins and I'll check the voltage tomorrow
Thanks for your help I'll let you know how I get on
-
22-03-2017 #9
-
22-03-2017 #10
Morning John, yes the voltage on the pins are about 3.3 v
So what do I need to do next
Thread Information
Users Browsing this Thread
There are currently 2 users browsing this thread. (0 members and 2 guests)
Similar Threads
-
Limit switch problem
By ECCO in forum General ElectronicsReplies: 7Last Post: 25-12-2015, 11:28 AM -
Another Home - Limit switch question
By Cube3 in forum General ElectronicsReplies: 6Last Post: 26-12-2013, 07:51 PM -
Limit and Home Switch Choice
By Wobblycogs in forum General ElectronicsReplies: 25Last Post: 02-12-2013, 06:16 PM -
FOR SALE: Z axis with Home/limit switch and Nema 23 3nm
By Shinobiwan in forum Items For SaleReplies: 6Last Post: 02-02-2013, 10:54 AM -
bounce off home switch.
By motoxy in forum Machine Control SoftwareReplies: 18Last Post: 30-08-2012, 12:26 PM
Bookmarks