[SOLVED] Limit switch issues

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15 Feb 2010 18:22 - 22 Feb 2010 18:37 #1914 by Pentax
hello again folks. first let me say thanks for all the help i recieved with the EMC stops but GUI continues issue, and I am so relieved to have it solved. so, now that i can jog the machine happily, and forever, in all directions, its time to mess with some gcode and run some test parts.

my question for the forum is... how in the heck do you hook up the limit switch? I'm running 7i43TA and 7i33 for servos.

The example says use the GPIO 25 pin for the limit switch (normally open). SO, I'm assuming this means hook up the switch to P4 (the servo port of of 7i43) pin 25, and throw the other side to a ground somewhere. I have tried this in every possible combination, and I seem to fail every time.... I can't really use EMC unless i can home the axis. is there any way to use EMC without homing? does anyone know what I am doing wrong? help is greatly appreciated.

thanks,
A
Last edit: 22 Feb 2010 18:37 by Pentax.

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16 Feb 2010 14:05 #1928 by BigJohnT
Replied by BigJohnT on topic Re:Limit switch issues
You can set no force homing in your ini file

www.linuxcnc.org/docview/html//config_ini_config.html#sub:[TRAJ]-section

I'm not sure about the wiring hopefully Peter will drop by and clear that up.

John

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17 Feb 2010 00:04 - 17 Feb 2010 00:14 #1937 by PCW
Replied by PCW on topic Re:Limit switch issues
Pin numbers in HostMot2 refer to logical pin numbers, not physical pin numbers, That's because you may have from 2 to 6 I/O connectors per FPGA card (so 2 to 6 pin 25s). A card like the 7I43 has a total of 48 I/O pins. These are numbered 0 through 47. On the 7I43, connector P4 has logical I/O pins 0 through 23 on odd physical pins 1 through 47, and connector P3 has logical I/O pins 24 through 47 on odd physical I/O pins 1 through 47. So your example of GPIO 25 is on pin 3 of P3.

The correspondence between physical and logical I/O pins is described in the .PIN file that matches the bit file, something like

/usr/share/doc/emc2-firmware-mesa-7i43-hostmot2/SVST4_4.PIN.gz
Last edit: 17 Feb 2010 00:14 by PCW. Reason: clarify

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17 Feb 2010 20:33 #1948 by Pentax
Replied by Pentax on topic Re:Limit switch issues
Thanks, Peter, and John. I will attempt both options, disabling force homing in the .ini file, and wiring the limit switch to P3 Pin 3 (assuming that is the third pin from the upper left if the slot is bottom).

John, i'm away from the machine now, but I will return on Saturday. what is the normal file path of the .ini file? I have the dapper drake install on this machine..

thanks,
A

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18 Feb 2010 00:04 - 18 Feb 2010 00:04 #1950 by BigJohnT
Replied by BigJohnT on topic Re:Limit switch issues
emc2/config off your home directory.

John
Last edit: 18 Feb 2010 00:04 by BigJohnT.

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21 Feb 2010 17:19 - 21 Feb 2010 17:41 #1975 by Pentax
Replied by Pentax on topic Re:Limit switch issues
Peter, I've connected the limit switch, in a normally open configuration, to P3 pin 3 and P3 pin 4. I'm assuming i am to use the even pins to complete the loop. Nothing happens. Am I doing something wrong? I'm assuming pin 3 is the pin that is 3rd from top left when the slot is at bottom.

AH! clearly, i just found this webpage...and clearly PIN 3 is not where i thought it would be...i'll try this out...

digital.ni.com/public.nsf/allkb/AE78263A...1D8B8625702F0082AD8D

ok that didn't work. so, i looked at the 7i33 which clearly has pin marked on the PCB at top left from bottom slot. So i went to the second pin over, the pin directly beneath that for ground and voila. it works. that standard pinout on that web page is not what the mesa board uses, but it did tell me that grounds and IO pins are top and bottom from one another. peter, maybe this is a good amendment for the 7i43 manual for electrical laymen like myself.


thanks for the help,
A
Last edit: 21 Feb 2010 17:41 by Pentax.

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22 Feb 2010 17:44 #1996 by PCW
Replied by PCW on topic Re:Limit switch issues
Sure, a physical pin-out chart would be good, but that drawing is flat out wrong!
There _is_ a standard pin-out for headers:
If you look carefully at the black 50 pin connector housing you will see a little
triangular mark for pin one (also the back of the cards have a square pad on pin one)

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